3. The correct answer is C. Endoderm refers to one of the three primary germ layers found in the initial phase of an embryo. The endoderm is the innermost layer. The cells going inwards along the archenteron produce the inner layer of the gastrula that forms into endoderm.
4. The correct answer is 3. The blastopore in a deuterostome develops into the animal's anus.
5. The correct answer is 2. A zygote refers to an amalgamation of a sperm cell and the egg cell. It is also called fertilized ovum, the zygote starts as a single cell, and however, it differentiates briskly in the days after fertilization.