Disruptive selection or diversifying selection describes the changes in population genetics where extreme values for a trait are favored over intermediate values.
So according to this definition, the conclusion can be derived as :
The most common circumference(s) to be after 10 generations of diversifying selection will be greater than 2 cm and less than 2 cm.
The answer is D) Stationary
(Not a 100% on this but, I'm like 90)
B temperature and precipitation