make a decision 还是 make the decision？

Question

( ) He has made _______ decision that he will be _______ inventor some time. A. a, the B. a, an C. the, an D. the, the

我觉得是C. 但参考答案是 B

Answer 1

中文意思不同，make a decision是做决定，而make the decision是做出决定。翻译一下意思完全不同呢