In which of these plants , the diploid stage of their life is dependent on the haploid stage of their life ?

Options

A. Riccia , Marchantia
B. Pinus, Cycas
C. Nephrolepis , Adiantum.
D. Hibiscus, Cycas

Answer

To solve the question regarding which plants have a diploid stage that is dependent on the haploid stage, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Life Cycle Stages**:
- Plants have two main stages in their life cycle: the haploid stage (gametophyte, represented as 'n') and the diploid stage (sporophyte, represented as '2n').
- In some plants, the sporophyte is dependent on the gametophyte for its nutrition and development.

2. **Identify Plant Categories**:
- Plants can be categorized into several groups:
- **Bryophytes** (e.g., mosses, liverworts)
- **Pteridophytes** (e.g., ferns)
- **Gymnosperms** (e.g., conifers)
- **Angiosperms** (e.g., flowering plants)

3. **Analyze Each Group**:
- **Bryophytes**: The main plant body is the gametophyte (haploid), and the sporophyte (diploid) is dependent on the gametophyte for nutrition. This is the key characteristic that makes bryophytes unique in this context.
- **Pteridophytes**: The sporophyte is dominant, and the gametophyte is independent and small.
- **Gymnosperms and Angiosperms**: Both have a dominant sporophyte stage, and the gametophyte is reduced and does not depend on the sporophyte.

4. **Evaluate the Options**:
- **Option A: Riccia and Marchantia**: Both are bryophytes, where the diploid sporophyte is dependent on the haploid gametophyte. This is a correct answer.
- **Option B: Pinus and Cycas**: These are gymnosperms, where the sporophyte is independent. Incorrect.
- **Option C: Adiantum**: This is a pteridophyte, where the sporophyte is dominant and independent. Incorrect.
- **Option D: Hibiscus**: This is an angiosperm, where the sporophyte is also dominant and independent. Incorrect.

5. **Conclusion**: The correct answer is **Option A: Riccia and Marchantia**, as they are bryophytes where the diploid stage (sporophyte) is dependent on the haploid stage (gametophyte).

### Final Answer:
**Option A: Riccia and Marchantia**