The fungal partner in a lichen mostly belongs to the group :

Options

A. Zygomycotina
B. Ascomycotina
C. Basidiomycotina
D. Deuteromycotina

Explanation

To solve the question regarding the fungal partner in a lichen, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Lichens**:
- Lichens are symbiotic organisms formed by the association of fungi and algae (or cyanobacteria). In this relationship, the fungus provides structure and protection, while the algae provide food through photosynthesis.

2. **Identifying the Fungal Groups**:
- The question lists four groups of fungi: Zygomycetes, Ascomycetes, Basidiomycetes, and Deuteromycetes. We need to determine which group predominantly comprises the fungal partner in lichens.

3. **Analyzing the Groups**:
- **Zygomycetes**: Generally do not form lichens.
- **Ascomycetes**: This group is known to be the most common fungal partner in lichens, with about 40% of lichen species having Ascomycete fungi.
- **Basidiomycetes**: These fungi are also not typically involved in lichen formation.
- **Deuteromycetes**: Known as "imperfect fungi," they are characterized by the absence of a known sexual reproduction stage and are less commonly associated with lichens.

4. **Conclusion**:
- Based on the information, the fungal partner in a lichen mostly belongs to the group **Ascomycetes** (Ascomycortina).

### Final Answer:
The fungal partner in a lichen mostly belongs to the group **Ascomycetes** (Ascomycortina).

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