In development of frog gastrulation involves
A) Epibody
B) Emboly
C) Invagination
D) All the above

Hint: In frog, gastrulation the cells of the blastula in the frog from the ectoderm or endoderm while the mesoderm is made from the yolk cells inside.

Complete Answer:
We will start with knowing about the development of frog gastrulation-
1)Gastrulation is a phase early in the embryonic development of most animals, during which the single-layered blastula is reorganized into a trilaminar structure known as the gastrula. These three germ layers are known as the ectoderm, mesoderm, and endoderm. In frogs, these layers are formed by the processes of epiboly, emboly and invagination.
2)The epibody consists of the epibolic movement is the way in which a layer of epithelial cells spread. This can be achieved in multiple ways.
3)The embryo is converted into a double-walled, cup-shaped structure. The new internal wall lines the archenteron, the newly formed cavity of the developing gut.
4)The emboly simply means the movement of the three germ layers i.e., ectoderm, mesoderm and endoderm, this process occurs in the blastocoel.
5)The opening of the archenteron to the exterior, the blastopore, is the site of the future anus in deuterostomes. Instead, cells from the animal pole move down the embryo surface; when they reach the region derived from the grey crescent, they move into the interior. These morphogenetic movements are called epiboly and emboly.
6)Then, the inward movement of invagination is accomplished as the cells change shape, first becoming flask- or bottle-shaped (so that most of their mass is actually below the surface) and then sinking into the interior as they lose their remaining connections with other cells on the surface.

Therefore, the correct answer is option D (All the above).

Note:The purpose of gastrulation in general is to position the 3 embryonic germ layers, the endoderm, ectoderm and mesoderm.