Whats the noun of inhabit by onlying adding a suffix

can you tell me the answers to this

the apollo program, also known as project apollo, was the third united states human spaceflight program carried out by the national aeronautics and space administration (nasa), which succeeded in landing the first humans on the moon from 1969 to 1972.

c is the answer because first she would blush to make the reader wonder why which they find out in the next line.

wheres the passage with the idiom underlined