What is the main role of the organ during development of foetus, which is formed by villi present in one of the membrane of trophoblast?

Explanation

### Step-by-Step Solution:

1. **Identify the Organ**: The organ formed by the villi present in the trophoblast during the development of the fetus is called the **placenta**.

2. **Understand the Formation**: The placenta is formed from the trophoblast layer of the blastocyst, which develops into the chorion. The villi are finger-like projections that extend into the uterine lining and help in the formation of the placenta.

3. **Main Functions of the Placenta**:
- **Nutritional Support**: The placenta facilitates the transfer of nutrients from the mother to the developing fetus, ensuring that the fetus receives essential vitamins and minerals for growth.
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