The correct answer is true. Both intramembranous ossification and endochondral ossification originates from a primary ossification center. The primary ossification center, as the name implies, is the focus where the bone tissue starts ossifying. Primary ossification centers are usually found in the diaphysis of long bones or in the body of irregular bones.
A dichotomous key uses questions or statements to help identify organisms, it also uses characteristics in it's questions ( that may be yes-no) and statements to help separate organisms from one another.