76. Which of the following statements concerning human embryonic development is correct?
(A) Inner cell mass is a group of cells that cluster at one end of the gastrula.
(B) The trophoblast, the outer epithelium of the gastrula, supports embryo growth.
(C) The trophoblast continues to expand into the endometrium, and four new extraembryonic membranes appear.
(D) By the end of blastocyst, three embryonic germ layers have formed.
(E) By the end of gastrulation, the extraembryonic ectoderm and extraembryonic membranes surround the embryo.