The recent discovery of the existence of a great number of planets than had previously been imagined only ____ undergirds the argument for intelligent lifeforms; such an argument depends on more than a mere collection of planets, for only those planets that can form a viable atmosphere can host the conditions necessary for life.
A. indirectly
B. instinctively
C. retroactively
D. subtly
E. ostensibly
문제의 핵심이
argument가 단순히 collection 말고도 다른것에도 의존한다는건데
x,y,z 라는 3개가 argument에 관련이 되어 있으면 x (collection)만 쓰면 안된다는 건데
이게 왜 D가 안되나요?
답은 A라고 하네요.