Which of the Following Can Be Considered Examples of Trait

Which of the following can be considered examples of trait variation being maintained by a fluctuating optimum level of a characteristic?
1) A rounder body shape is favored in cold climates,but a longer body shape is favored in hot climates
2) Rapid growth is favored if there is much vegetation,but slow growth is favored if there is little vegetation
3) A cautious style is favored if there are many predators,but a bolder style is favored if there are few predators.

A) 1 only
B) 1 and 2 only
C) 1 and 3 only
D) 2 and 3 only
E) 1,2,and 3