One of the main evolutionary features of the alternation of generations from algae to flowering plants is.

Options

A. gradual elaboration of gametophyte
B. gradual elaboration of sporophyte
C. elimination of sporophytic tissue
D. elimination of gametophyte.

Answer

### Step-by-Step Solution:

1. **Understanding the Terms**:
- **Gametophyte**: This is the haploid phase of the plant life cycle that produces male and female gametes through sexual reproduction.
- **Sporophyte**: This is the diploid phase that produces spores through asexual reproduction.

2. **Concept of Alternation of Generations**:
- The life cycle of plants involves two distinct phases: the haploid gametophyte and the diploid sporophyte. This phenomenon is known as alternation of generations or metagenesis.

3. **Evolutionary Progression**:
- As we move from simpler forms of plants like algae to more complex forms like flowering plants, there is a notable evolutionary trend in the development of these two phases.
- In algae, the gametophyte phase is often dominant, whereas in flowering plants, the sporophyte phase becomes more prominent.

4. **Key Evolutionary Feature**:
- The main evolutionary feature observed in the transition from algae to flowering plants is the **gradual elaboration of the sporophyte**. This means that the sporophyte phase becomes more complex and multicellular, while the gametophyte phase tends to be reduced.

5. **Conclusion**:
- Based on the understanding of the alternation of generations and the evolutionary trends, the correct answer to the question is **option B: gradual elaboration of sporophyte**.