_______do not have free living gametophyte.

Options

A. Bryophytes
B. Pteridophyte.
C. both a and b
D. gymnosperm

Explanation

To solve the question "_______ do not have free living gametophyte," we need to analyze the options provided and understand the characteristics of the plant groups mentioned.

### Step-by-Step Solution:

1. **Understand the Concept of Gametophytes**:
- In the plant life cycle, gametophytes are the haploid phase that produces gametes (sperm and eggs). Free-living gametophytes can exist independently from the sporophyte.

2. **Identify the Groups Mentioned**:
- The options provided are:
- A) Bryophytes
- B) Pteridophytes
- C) Both A and B
- D) Gymnosperms

3. **Analyze Bryophytes**:
- Bryophytes (like mosses) have a dominant gametophyte stage that is free-living. Therefore, they do have free-living gametophytes. This option is incorrect.

4. **Analyze Pteridophytes**:
- Pteridophytes (like ferns) also have a free-living gametophyte stage known as prothallus. Thus, this option is also incorrect.

5. **Analyze Both A and B**:
- Since both Bryophytes and Pteridophytes have free-living gametophytes, this option is incorrect as well.

6. **Analyze Gymnosperms**:
- Gymnosperms do not have free-living gametophytes. The male and female gametophytes are retained within the sporangia on the sporophyte. The male gametophyte is found in microsporangia, and the female gametophyte is found in megasporangia. This option is correct.

7. **Conclusion**:
- The correct answer to the question is **Gymnosperms**.

### Final Answer:
**Gymnosperms do not have free living gametophyte.**