Why Might Researchers Sometimes Want to Measure the Specific Personality

Why might researchers sometimes want to measure the specific personality traits that make up each of the major dimensions (factors) of personality,instead of just measuring those few broad dimensions?

A) It is much more efficient to measure many specific personality traits than to measure only a few broad personality factors.
B) Only the specific personality traits can be measured with adequate reliability and content validity,which means that only the specific traits have any usefulness in practical settings.
C) Sometimes a specific personality trait is likely to be especially strongly related to the variables that one wants to predict (much more so than other traits within the same factor) .
D) All of the above.
E) None of the above;the discovery of the major factors has made this practice completely unnecessary.