Heterosporous pteridophytes show certain characteristics, which are precursor to the seed habit in gymnosperms. One of such characteristics is

Options

A. a) presence of vascular tissues
B. b) external water required for fertilisation
C. c) presence of embryo stage
D. d) development of embryo inside the female gametophyte.

Explanation

To answer the question regarding the characteristics of heterosporous pteridophytes that are precursors to the seed habit in gymnosperms, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Heterospory**:
- Heterosporous pteridophytes are those that produce two distinct types of spores: microspores (male) and megaspores (female).
- Example genera include Selaginella and Salvinia.

2. **Identify the Spores**:
- Microspores are smaller and develop into male gametophytes.
- Megaspores are larger and develop into female gametophytes.

3. **Germination of Spores**:
- Upon germination, the microspores lead to the formation of male gametophytes, while megaspores lead to female gametophytes.

4. **Fertilization Process**:
- The male gametes (from the male gametophyte) travel to the female gametophyte where fertilization occurs.
- This process takes place within the confines of the female gametophyte.

5. **Development of the Zygote**:
- After fertilization, the zygote develops into a young embryo, and this development occurs inside the female gametophyte.
- This internal development is significant as it is a precursor to the seed habit.

6. **Conclusion**:
- The characteristic that serves as a precursor to the seed habit in gymnosperms is the development of the embryo inside the female gametophyte.

### Final Answer:
The characteristic of heterosporous pteridophytes that is a precursor to the seed habit in gymnosperms is **the development of the embryo inside the female gametophyte**.

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