Phytoplankton is made of

Options

A. Decomposer microorganisms
B. Plants feeding on animals and their remains
C. Aquatic algae and photosynthetic bacteria
D. Non-vascular hydrophytes.

Answer

**Step-by-Step Solution:**

1. **Understanding Phytoplankton**: Phytoplankton are microscopic organisms that live in aquatic environments. They are primarily responsible for photosynthesis in these ecosystems, producing oxygen and serving as a primary food source for many aquatic animals.

2. **Analyzing the Options**:
- **Option A**: Decomposer microorganisms - This is incorrect because phytoplankton are not decomposers; they produce energy through photosynthesis.
- **Option B**: Plants feeding on animals and their remains - This is also incorrect as phytoplankton do not feed on animals; they are producers, not consumers.
- **Option C**: Aquatic alga and photosynthetic bacteria - This is correct. Phytoplankton primarily consist of these two groups, which perform photosynthesis.
- **Option D**: Non-vascular hydrophytes - This is incorrect as non-vascular plants do not encompass the full range of phytoplankton.

3. **Conclusion**: Based on the analysis, the correct answer is **Option C: Aquatic alga and photosynthetic bacteria**.

---