The Embryonic Phase Differs from the Pre-Embryonic Phase Because

The embryonic phase differs from the pre-embryonic phase because

A) the embryonic phase occurs during the first 2 weeks of pregnancy, while the pre-embryonic phase describes the period from 2 to 8 weeks of pregnancy.
B) the embryonic phase is initiated by zygote formation, whereas the pre-embryonic phase is initiated by blastocyst formation.
C) the embryonic phase begins at week 9 of pregnancy, while the pre-embryonic phase begins at week 2.
D) organ formation and development begin during the embryonic phase, whereas blastocyst formation occurs in the pre-embryonic phase.