Name the three sub-kingdoms of Protista as proposed by Robert H. Whittaker.

Explanation

### Step-by-Step Text Solution:

1. **Understanding the Classification System**: Robert H. Whittaker proposed a five-kingdom classification system in 1969, which includes Monera, Protista, Fungi, Plantae, and Animalia.

2. **Identifying Protista**: The kingdom Protista consists of unicellular and simple microorganisms that do not fit into the categories of plants, animals, or fungi.

3. **Subdividing Protista**: Protista is further divided into three sub-kingdoms based on their characteristics:
- **Chrysophytes**: These are plant-like protists that can perform photosynthesis. They include organisms like diatoms and dinoflagellates.
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