Major photosynthetic planktons are

Options

A. Chrysophytes
B. Dinoflagellates
C. Green algae
D. 1 and 2

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the major photosynthetic planktons. We need to identify which organisms are classified as such.

2. **Defining Plankton**: Plankton are small organisms that drift in water bodies. They can be classified into two main types: zooplankton (animal plankton) and phytoplankton (plant plankton). Since the question specifies "photosynthetic planktons," we focus on phytoplankton.

3. **Identifying Phytoplankton**: Phytoplankton are the primary producers in aquatic ecosystems. They perform photosynthesis, converting sunlight into energy, and are essential for the marine food web.

4. **Listing Major Types of Phytoplankton**: The major types of phytoplankton include:
- **Diatoms**: These are a major group of microalgae and are known for their silica cell walls. They are significant contributors to photosynthesis in aquatic environments.
- **Dinoflagellates**: These are another group of phytoplankton characterized by their two flagella, which allow them to move through water. They are also important photosynthetic organisms.

5. **Analyzing the Options**: The options provided are:
- 1. Chrysophytes
- 2. Dinoflagellates
- 3. Green algae
- 4. 1 and 2

From our identification, we see that both diatoms (which fall under chrysophytes) and dinoflagellates are major photosynthetic plankton.

6. **Conclusion**: Since both chrysophytes (which include diatoms) and dinoflagellates are significant contributors to photosynthesis in aquatic environments, the correct answer is option 4: "1 and 2".

**Final Answer**: The major photosynthetic planktons are chrysophytes and dinoflagellates (Option 4: 1 and 2).

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