Which of the Following Statements About Early Development in Marsupials

Multiple Choice

Which of the following statements about early development in marsupials is CORRECT?

A) The eggs of marsupials are virtually yolk-free, so the blastomeres are all of a similar size.
B) The tissues of the embryo proper are derived from a specific set of blastomeres, clustered together to form an inner cell mass, at one end of the blastula.
C) The first cleavage division is vertical, but the second cleavage division is horizontal in one blastomere and vertical in the other.
D) The egg is surrounded by external envelopes, which are porous to uterine secretions that nourish the embryo until it implants.
E) The egg is yolk rich and the first three divisions are unequal.