Point out the odd one

Options

A. nucellus
B. embryo sac
C. micropyle
D. pollen grain

Explanation

To solve the question "Point out the odd one," we need to analyze the four terms provided: nucellus, embryo sac, micropyle, and pollen grain. Here’s a step-by-step breakdown of the solution:

### Step-by-Step Solution:

1. **Identify the Terms**:
- The terms given are: **nucellus**, **embryo sac**, **micropyle**, and **pollen grain**.

2. **Understand Each Term**:
- **Nucellus**: This is the central part of the ovule and contains the embryo sac.
- **Embryo Sac**: This is located within the ovule and contains the egg cell.
- **Micropyle**: This is a small opening in the surface of the ovule.
- **Pollen Grain**: This is a microscopic structure that contains male reproductive cells.

3. **Categorize the Terms**:
- The first three terms (nucellus, embryo sac, micropyle) are all parts of the **ovule**.
- The **pollen grain**, on the other hand, is part of the **male reproductive system** and is involved in fertilization.

4. **Determine the Odd One Out**:
- Since the nucellus, embryo sac, and micropyle are all components of the ovule, while the pollen grain is not, we can conclude that the **pollen grain** is the odd one out.

5. **Final Answer**:
- The odd one out is **pollen grain**.