Well defined nucleus is absent in

Options

A. Paramecium
B. Pseudomonas
C. Algae
D. Fungi

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which organism does not have a well-defined nucleus. This means we need to identify whether the organism falls under prokaryotes or eukaryotes.

2. **Identifying the Options**: The options provided are:
- Paramecium
- Pseudomonas
- Algae
...