Answer:
C. 30
Explanation:
15 men do work in 16 days
This means that 7.5 men (15/2) would do that same work in 32 days (16x2).
If the number of men increase, the amount of days decrease.
8 men would do that work in 30 days
8 men > 7.5 men
30 days < 32 days