Which pteridophyte has been proved to be a good biofertilizer for paddy?

Options

A. Azolla
B. Marsilea
C. Pteris
D. Selaginella

Explanation

**Step-by-Step Solution:**

1. **Understanding Pteridophytes**: Pteridophytes are vascular plants that reproduce via spores rather than seeds. They do not produce flowers or seeds.

2. **Identifying the Options**: The question provides four options: Azolla, Marsilia, Pteris, and Cilaginela. We need to determine which of these is known to be a good biofertilizer for paddy.

3. **Analyzing Azolla**: Azolla is a type of pteridophyte that floats on water. It is known for its ability to fix nitrogen due to the presence of a cyanobacterium called Anabaena azollae.

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