All of the Following Are Limitations of Allport's Ideas or Work

All of the following are limitations of Allport's ideas or work, except one. Which is NOT a limitation?

A) His "theory" is really a series of mini-theories.
B) His insistence on the extreme uniqueness of each person makes the task of understanding humans look very daunting.
C) The boundaries between some of his concepts are so indistinct as to be exceedingly hazy.
D) He vacillated concerning what he meant by nearly all of his terms: publications a year or two apart contained changes in definitions that were left unacknowledged.