Two modifiers modify a noun

[RonPurewal]

nb:
note that there are no official problems——nada, zero——with such an amazing density of "big" words as is found here. i mean, i'm too lazy to count, but the average for each answer choice appears to be something like 10 letters per word (!!).

this is a big deal, because the official problems are generally written so that their meaning can be understood quickly and without a great deal of trouble. (remember, Step One = ignore grammar; get intended meaning.)
if you become accustomed to practice materials in which the intended meaning is hard to extract, there may be negative returns on test day.

[AsadA969]

ok. a construction like choice B is possible. here's an example:
In 1989, taking a road trip across the country, I met the man who would become my best friend.

here's how this works:
In 1989, (taking a road trip across the country, (I met the man who would become my best friend)).

i hope the colors make sense.
"in 1989" modifies the entire orange sentence, including the modifier that opens that sentence ("taking...").
"taking a road trip..." describes the blue sentence, as is standard for such modifiers.

the problem is that choice (b) doesn't work this way.
if we use the same colors for choice (b), then "in ... illustrations" (remember, i'm discussing the OG problem) is supposedly describing everything that follows——including "coordinating...".
that's nonsense, though, because, clearly, that coordination doesn't happen IN the illustrations.
rather, it's just an additional fact about the illustrations——a purpose for which the "___, which..." modifier (as in the correct answer) is perfect.

Ron, thanks for your creative example. But, your answer is slightly different to my question. Now, I am trying with my level best to make clear you.
In your example, you've shown that :
"in 1989" modifies the entire orange sentence, including the modifier that opens that sentence ("taking...").
"taking a road trip..." describes the blue sentence, as is standard for such modifiers.
But, I wanna have an example in which BOTH
"in 1989"(assume it is first part of the sentence) and "taking a road trip across the country" (assume it is second part of the sentence) SIMULTANEOUSLY modify "I met the man who would become my best friend" (assume it is third part of the sentence).

or, another example in which BOTH 2nd part and 3rd part modify the 1st part SIMULTANEOUSLY.

or, BOTH 1st part and 3rd part will modify SIMULTANEOUSLY the 2nd part.

Thanks.

In addition, By using AT A TIME ( YOUR PURPLE SIGN) I wanted to mean SIMULTANEOUSLY.

[RonPurewal]

we seem to have strayed into territory that's irrelevant to the GMAT.

if you can produce a GMAT item that's related to this query, please do.

[harshdeeps758]

Thanks Ron. This is useful

[RonPurewal]

you're welcome.