GRE big book test 3 section 3 question 6

GRE Verbal Problem Solving
1

Hey, I tried to solve this question but don’t really understand the answer in the Answer key. Can anyone help me to explain this? Any help would be greatly appreciated

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  • this is a support
  • i guess blank 1 = useful or popular, blank 2 = used by. This led me to 2 answers B and E
  • but I don’t know how to choose the better one
2

How does “popular” support “used by”?

3

hey @ganesh, actually I guess blank 2 = used by first, and for blank 1, I think if you test ____ of borrowing from one filed of study to enrich another, it could be you’re checking it’s efficency or populariry. So I guess blank 1 = useful or popular