You Are Measuring the Trait of Friendliness in a Set

You are measuring the trait of friendliness in a set of 100 monozygotic twins. You notice that for almost all of the twins, when one is high on this measure, the other twin is also high. We would say that the trait of friendliness has

A) low reaction range
B) low heritability
C) high selection pressure
D) high genetic flow
E) high concordance