Figure 21.3 in a Very Large Population, a Quantitative Trait Has the Has

Figure 21.3
In a very large population, a quantitative trait has the distribution pattern shown in Figure 21.3. If the curve in Figure 21.3 shifts to the left or to the right, there is no gene flow, and the population size consequently increases over successive generations. Which of the following is (are) probably occurring?
1) immigration or emigration
2) directional selection
3) adaptation
4) genetic drift
5) disruptive selection

A) 1 only
B) 4 only
C) 2 and 3
D) 4 and 5
E) 1, 2, and 3