Indoor air pollution can threaten the health of closely conf

[MdAbuAsad]

Indoor air pollution can threaten the health of closely confined farm animals and the workers who tend them and perhaps as well impairs the quality of such farm products like eggs, poultry, and pork.

(A) perhaps as well impairs the quality of such farm products like
(B) perhaps as well impairs the quality of such farm products as
(C) perhaps also impairs the quality of such farm products like
(D) may also impair the quality of such farm products like
(E) may also impair the quality of such farm products as

[MdAbuAsad]

Indoor air pollution can threaten the health of closely confined farm animals and the workers who tend them and perhaps as well impairs the quality of such farm products like eggs, poultry, and pork.

(A) perhaps as well impairs the quality of such farm products like
(B) perhaps as well impairs the quality of such farm products as
(C) perhaps also impairs the quality of such farm products like
(D) may also impair the quality of such farm products like
(E) may also impair the quality of such farm products as

Indoor air pollution can threaten the health of closely confined farm animals and the workers who tend them and may also impair the quality of such farm products as eggs, poultry, and pork..
if we don't use a COMMA before last AND this part misguide us, isn't it? Does GMAT do it intentionally?
what if the part is something like below?
Indoor air pollution can threaten the health of closely confined farm animals and the workers who tend them ,and may also impair the quality of such farm products as eggs, poultry, and pork.

[Whit Garner]

Hi MdAbuAsad!

I can see how this might feel confusing, but there are very specific rules about when we do and don't use a comma before an "and." In fact, there are only three occasions for using the period.

1) A 3-(or more)-Item List: My sister loves to bake cakes, cookies, and pies.

2) A modifier interjected in a two item list: My sister loves to bake cakes, particularly for weddings, and pies.

3) A coordinating conjunction connecting two independent clauses: My sister loves to bake cakes, and she has been selling them successfully for years.

Notice that in the example sentence you provided, the latter and ("and perhaps as well impairs") isn't before the third item in a list, doesn't have a modifier in front of it, and isn't followed by a complete sentence. Therefore, you do not use a comma before that and.

Hope this helps!

Whit

[MdAbuAsad]

Indoor air pollution can threaten the health of closely confined farm animals and the workers who tend them and perhaps as well impairs the quality of such farm products like eggs, poultry, and pork.

(A) perhaps as well impairs the quality of such farm products like
(B) perhaps as well impairs the quality of such farm products as
(C) perhaps also impairs the quality of such farm products like
(D) may also impair the quality of such farm products like
(E) may also impair the quality of such farm products as

Indoor air pollution can threaten the health of closely confined farm animals and the workers who tend them and may also impair the quality of such farm products as eggs, poultry, and pork..
if we don't use a COMMA before last AND this part misguide us, isn't it? Does GMAT do it intentionally?
what if the part is something like below?
Indoor air pollution can threaten the health of closely confined farm animals and the workers who tend them ,and may also impair the quality of such farm products as eggs, poultry, and pork.

Thanks for the reply Whit! I am going to quote my post again to clarify the situation!
If this is the case then it seems that ''the workers tend them and (the workers) may also impair the quality''! is it the right meaning? Shouldn't it be like ''Indoor air pollution can threaten...... and may also impair the quality..''?
I think you get my point!

[Whit Garner]

You have a list embedded in a list. A simpler example: On vacation, I like to try unique foods and beverages and visit museums and gardens. I have the main list: On vacation, I like to try (some stuff) and visit (some places). This is a 2 items list and doesn't fit any of the qualifications that would suggest a comma before the AND so there isn't one. The fact that within each list item is a sub list (eg. food and bevs or museums and gardens), doesn't change that fact.