The old scientist devoted most of his time ____ the space science.

A. develop B. to developing C. to develop D. developing

B

句意：这位老科学家把他的大部分时间用在发展空间科学上。devote sth. to sth.把……用于……，固定表达，to是介词，后接名词或动名词。根据句意结构，可知选B。