Epiboly is the process of

Options

A. Rotation of gastrula within vitelline membrane so that animal pole becomes anterior
B. Overgrowth of micromeres which divide rapidly and spread downward over megameres except at yolk plug
C. Mass migration of cells from animal hemisphere so that upper micromeres migrate over edge of dorsal lip, roll inside and fucked beneath outer layer
D. Formation of small slit like invagination upon grey crescent

Answer

B

Explanation

Epiboly - descending of dividing cells to cover other cells. Invagination - tucking in blastula wall. Emboly - Upward movement of dividing cells underneath the cells.