Haplo-diplontic life cycle is found in

Options

A. bryophytes
B. pteridophytes
C. fungi
D. both a and b

Explanation

### Step-by-Step Solution:

1. **Understanding the Term "Haplo-Diplontic Life Cycle":**
- The haplo-diplontic life cycle refers to a life cycle that includes both haploid (n) and diploid (2n) stages. In this cycle, there is a clear alternation of generations between the haploid gametophyte and the diploid sporophyte.

2. **Identifying the Phases:**
- The life cycle is divided into two main phases:
- **Haploid Phase (Gametophyte):** This phase produces gametes (sperm and eggs) and is characterized by having a single set of chromosomes (haploid).
- **Diploid Phase (Sporophyte):** This phase produces spores and is characterized by having two sets of chromosomes (diploid).

3. **Examples of Organisms with Haplo-Diplontic Life Cycle:**
- The question asks which groups of organisms exhibit this type of life cycle.
- **Bryophytes:** These include mosses, liverworts, and hornworts. They have a dominant gametophyte stage and a shorter sporophyte stage.
- **Pteridophytes:** These include ferns and horsetails. They also exhibit a dominant sporophyte stage but have a significant gametophyte stage as well.

4. **Conclusion:**
- Both bryophytes and pteridophytes exhibit the haplo-diplontic life cycle. Therefore, the correct answer to the question is **both A and B** (which refers to both bryophytes and pteridophytes).

### Final Answer:
The haplo-diplontic life cycle is found in **both A and B** (bryophytes and pteridophytes).

---