One report concludes

[vaibhavsharma1988]

gmat prep 1

question : One report concludes that many schools do not have or likely to have, enough computers to use them effectively.

a) or
b) nor
c) or are
d) nor are they
e) nor are not

answer d)

my question : how to choose the correct answer between option c) & d).

[RonPurewal]

to the original poster:
i've noticed a couple of brand-new threads by you, on problems for which there are already existing threads that already answer the question(s) that you're posing.
please SEARCH THE FORUM for existing threads dealing with the problem that you're posting.
it should be really, really easy to find the threads for sentence correction problems, since you can use any string of consecutive words from the sentence as a search string -- just highlight a group of words from the sentence, put it in quotes, use it as a search term, and you should find the relevant thread(s) without much of an issue. (this is how i find threads to which i can refer posters such as you.)

for this problem, see the following:
post21473.html#p21473
and
post35718.html#p35718

if you have further questions after you've read those, please post them on THAT thread, not on this one. we'll delete additional questions that are posted on this thread.