Part of primitive gut is

Options

A. Yok sac
B. Embryonic disc
C. Trophoblst
D. Inner cell mass.

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about a part of the primitive gut. The primitive gut is an early structure in embryonic development that eventually forms the digestive tract.

2. **Identifying Options**: The options provided are:
- A) Yolk sac
- B) Embryonic disc
- C) Trophoblasts
- D) Inner cell mass

3. **Analyzing Each Option**:
- **Yolk Sac**: This structure is present early in development, around 3 days of gestation. It plays a crucial role in early embryonic development and acts as a primitive circulatory system. It is also involved in the formation of the primitive gut.
- **Embryonic Disc**: This is a flat structure that forms the embryo but does not directly contribute to the primitive gut.
- **Trophoblasts**: These are cells that form the outer layer of the blastocyst and are involved in implantation and nutrient exchange, but they do not form part of the gut.
- **Inner Cell Mass**: This is the cluster of cells in the blastocyst that will develop into the embryo but does not directly form the primitive gut.

4. **Conclusion**: The yolk sac is the structure that is part of the primitive gut. It is integrated into the body of the embryo during the folding process around the fourth week of gestation.

5. **Final Answer**: The part of the primitive gut is **A) Yolk sac**.