A seed is :

Options

A. a female gametophyte
B. a mature pollen tube
C. a mature ovule .
D. an immature embryo

Explanation

### Step-by-Step Solution:

1. **Understanding the Definition of a Seed**:
- A seed is the reproductive unit of flowering plants and is formed after fertilization. It contains an embryonic plant and is crucial for the plant's reproduction.

2. **Analyzing the Options**:
- **Option A: Female Gametophyte**:
- The female gametophyte is a structure within the ovule that contains the egg cell and is involved in fertilization. It is not a seed itself.
- **Option B: Mature Pollen Tube**:
- The mature pollen tube is formed from the male gametophyte and is responsible for delivering sperm cells to the ovule. It is not related to the seed.
- **Option C: Mature Ovule**:
- A mature ovule is the structure that, after fertilization, develops into a seed. This option closely relates to the definition of a seed.
- **Option D: Immature Embryo**:
- An immature embryo is part of the seed. However, a seed itself is not just an immature embryo; it is a mature structure that includes the embryo and seed coat.

3. **Identifying the Correct Answer**:
- Based on the analysis, the correct answer is **C: Mature Ovule**, as a seed is essentially a mature ovule that has developed after fertilization.

### Final Answer:
A seed is a **mature ovule**.

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