Embryo sac is to ovule as_________is to an anther.

Options

A. stamen
B. filament
C. pollen grain
D. androecium

Explanation

To solve the analogy "Embryo sac is to ovule as _______ is to an anther," we need to understand the relationship between the terms involved.

### Step-by-Step Solution:

1. **Identify the Role of the Embryo Sac:**
- The embryo sac is the female gametophyte in flowering plants. It is located within the ovule and is responsible for the development of the female gametes (eggs).

2. **Understand the Relationship:**
- The embryo sac is contained within the ovule, which is a part of the ovary in the female reproductive structure of the flower.

3. **Identify the Male Equivalent:**
- The anther is the part of the male reproductive structure (stamen) that produces pollen grains, which are the male gametophytes.

4. **Determine the Corresponding Term:**
- Just as the embryo sac is to the ovule, the pollen grain is to the anther. The pollen grain is produced in the anther and represents the male gamete.

5. **Select the Correct Answer:**
- Therefore, the correct answer to fill in the blank is "pollen grain."

### Final Answer:
Embryo sac is to ovule as **pollen grain** is to an anther.

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