Gastrula is the embryonic stage in which

Options

A. cleavage occurs
B. blatocoel form
C. germinal layers
D. villiform.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Gastrula Stage**: The gastrula is an important embryonic stage that follows the blastula stage in the development of an embryo. It is characterized by the formation of germ layers.

2. **Identifying Key Processes**: During the gastrula stage, a process called gastrulation occurs. This involves the rearrangement of cells that leads to the formation of three primary germ layers: ectoderm, mesoderm, and endoderm.

3. **Formation of Germ Layers**: The inner cell mass of the blastocyst differentiates into these three germ layers. Each layer will eventually give rise to different tissues and organs in the developing organism.

4. **Conclusion**: Therefore, the gastrula is the embryonic stage in which the germ layers are formed from the inner cell mass. The correct answer to the question is that the gastrula is the stage where germinal layers are differentiated.

**Final Answer**: The gastrula is the embryonic stage in which the germinal layers are formed.

---