In this question, sentence is given with blank to be filled in with an appropriate word. Four alternatives are suggested for question. Choose the correct alternative out of the four.
Mr. Obi put his whole life ______ the work.

Options

A. on
B. in
C. into
D. upon

Answer

B

Explanation

put something in something (Idiom) : to spend a lot of time or make a lot of effort doing something.
Here, in is the right usage.