Rickooreo wrote:
Bro have a few doubt in this question,
1. In option A and B, what is "it" referring to? Is it mandatory
The "it" doesn't really refer to any concrete thing. These "non-referential" pronouns are rare on the GMAT and not worth worrying too much about, but we have seen them in OAs (
here, for example). For more on non-referential pronouns, check out this thread:
https://gmatclub.com/forum/for-those-wh ... l#p1829681.
Quote:
2.
Option A : Option to study the effects of calefaction, or warming, of a river in greater detail
Option C : made it possible to study in greater detail than ever before the effects of calefaction,
Study is of calefaction, so shouldn't the modifier be together and hence elimiante C?
I'm not 100% sure which "modifier" you're referring to, but the phrase "in greater detail than ever before" modifies "to study." This modifier doesn't NEED to touch the thing it modifies, but if anything this is a vote in favor of (C) over (A).
The prepositional phrase "of calefaction" modifies "the effects," so "the effects of calefaction" is fine in (C). And "the effects" are just the thing being studied (not a modifier), and there's no reason for it to appear immediately after "to study".
Separating "in greater detail" from "to study" in (A) is probably worse than separating "the effects" from "to study" in (C). (A) seems to suggest that the river itself was "in greater detail," and obviously that doesn't make sense.
But that's certainly not a reason to eliminate (A) right away. In general, there are no clear-cut rules defining this sort of thing, so you want to be very conservative.
Quote:
3. Option B
possible to study, in greater detail, the effects of calefaction, or warming, of a river
Analysis of option B :
a) in greater detail is between two commas making it non-essential, however it seems to be important to convey the meaning of the passage, on this basis can I eliminate B?
b) Similarly will it apply to " , or warming , "
Option C : How is the usage of "have made" correct? New technique means recently discovered and we use past perfect when saying something started in the past but continues in the present.
When did the new techniques make it possible to study the effects in greater detail? Was it a specific moment in the past? Is it the present?
Logically, it makes a lot of sense that this was a gradual process -- using those techniques to study the effects in greater detail is something that began when the techniques came into existence (some time in the past) and continues into the present (those techniques STILL make it possible to study the effects in greater detail), so the present perfect makes sense here.
More broadly, there is some flexibility when it comes to the present perfect, and the action might not necessarily continue into the present. For example:
"Tim has taken the GMAT 8 times."
This doesn't mean that Tim is STILL taking the GMAT at the present moment. We don't know exactly when Tim took the exams, but we know that he must have taken them between some moment in the past and the present moment. So the present perfect makes sense.
The takeaway: as with most things on GMAT SC, make sure you aren't being overly rigid with the grammar "rules".
I hope that helps!