Protists are:
1. Unicellular and prokaryote
2. Unicellular and eukaryote
3. Multicellular and eukaryote
4. Autotroph and heterotroph

Options

A. 1,2 and 3
B. 2,3 and 4
C. 3 and 4
D. 2 and 4

Answer

To solve the question regarding the characteristics of protists, we will analyze each of the provided options step by step.

### Step-by-Step Solution:

1. **Understanding Protists**:
- Protists are a diverse group of eukaryotic microorganisms. They can be unicellular or multicellular, but most are unicellular.

2. **Evaluating Option 1**:
- **Option 1** states that protists are "unicellular and prokaryote".
- This is incorrect because protists are eukaryotic organisms, not prokaryotic. Prokaryotes lack a defined nucleus, while protists have a well-defined nucleus.

3. **Evaluating Option 2**:
- **Option 2** states that protists are "unicellular and eukaryote".
- This is correct. Most protists are unicellular and they are classified as eukaryotes due to the presence of a nucleus and other membrane-bound organelles.

4. **Evaluating Option 3**:
- **Option 3** states that protists are "multicellular and eukaryote".
- This is incorrect. While there are some multicellular forms in the broader category of protists (like certain algae), the majority are unicellular. Therefore, this statement is misleading as it implies that all protists are multicellular.

5. **Evaluating Option 4**:
- **Option 4** states that protists are "autotroph and heterotroph".
- This is correct. Protists can be autotrophic (like algae that perform photosynthesis) or heterotrophic (like protozoans that consume organic material).

### Conclusion:
Based on the evaluation of the options, the correct characteristics of protists are found in options 2 and 4. Therefore, the answer to the question is:

**Answer: 2 and 4 are correct.**