A Difference Between a Primary Follicle and a Primordial Follicle

A difference between a primary follicle and a primordial follicle is that

A) the oocyte is larger in the primordial follicle.
B) the primary follicle is an earlier stage than the primordial follicle.
C) one has an antrum and the other does not.
D) the primordial follicle has only a single layer of flat follicular cells, whereas the primary follicle is comprised of cuboidal follicle cells.