The proces by which primary germinal layers are formed is called

Options

A. Blastulation
B. Cleavage
C. Gastrulation
D. Implanatation

Answer

To solve the question regarding the process by which primary germinal layers are formed, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for the name of the process that leads to the formation of primary germinal layers during embryonic development.

2. **Identify the Options**: The options given are:
- A. Blastulation
- B. Cleavage
- C. Gastrolation
- D. Implantation

3. **Define Each Process**:
- **Blastulation**: This is the stage where the blastula is formed, which is a hollow sphere of cells. It occurs after cleavage.
- **Cleavage**: This refers to the series of rapid cell divisions that occur after fertilization, leading to the formation of a multicellular embryo.
- **Gastrolation**: This is the process that follows cleavage and involves the rearrangement of cells to form the three primary germ layers: ectoderm, mesoderm, and endoderm.
- **Implantation**: This is the process where the embryo attaches to the uterine wall, which occurs after the formation of the blastocyst.

4. **Determine the Correct Answer**: Since the question specifically asks for the formation of primary germinal layers, the correct answer is **C. Gastrolation**. This is the stage where the three germ layers are established.

5. **Conclusion**: The process by which primary germinal layers are formed is called **Gastrolation**.

### Final Answer:
The correct option is **C. Gastrolation**.