Classify bacteria into four types based on their shapes.

Explanation

To classify bacteria based on their shapes, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definition of Bacteria**:
- Bacteria are unicellular organisms that belong to the prokaryotic group. This means they consist of a single cell and lack a true nucleus and other membrane-bound organelles.

2. **Identify the Different Shapes of Bacteria**:
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