himanshu0123
how do I get to the crux of parallelism here. It is very confusing whether ''costly'' can be used for both the parts of 'and' or just one part
In this context, it's plain that both of the agricultural processes are expensive/"costly".
I see what you're saying here—you're seeing "costly X and Y" and claiming that it's not possible to tell whether the intention is "costly (X and Y)" or just "(costly X) and Y".
From the context alone, though, you should be able to deduce that it's the former of these (which is
not straightforward to write in a way that totally gets rid of this supposed ambiguity—try it!). Also note that if the latter interpretation were intended, then a good writer would simply invert the order of the elements ("Y and costly X") to produce a completely unambiguous phrasing that's still compact.
This isn't the issue to get stuck on, since there are more black-and-white ways to make eliminations here.
For instance, in choice D the singular verb "was" disagrees with its subject (which has the form "x and y" and therefore must be plural)—and all three of choices A, B, and C mistakenly state that the
requirements, rather than the expensive/resource-demanding processes themselves, are "costly".