Single celled organisms are called _______

Options

A. unicellular
B. multicellular
C. both of these
D. none of these

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the term used to describe single-celled organisms.

2. **Identifying Options**: We have four options to choose from:
- Option 1: Unicellular
- Option 2: Multicellular
- Option 3: Both of these
- Option 4: None of these

3. **Defining Unicellular**: Unicellular organisms are those that consist of only one cell. An example of a unicellular organism is amoeba, which is made up of a single cell.

4. **Defining Multicellular**: Multicellular organisms are those that are made up of more than one cell. Examples include plants and animals, which can have millions of cells.

5. **Analyzing the Options**:
- Option 1 (Unicellular) is correct because it directly refers to single-celled organisms.
- Option 2 (Multicellular) is incorrect because it refers to organisms made up of multiple cells.
- Option 3 (Both of these) is incorrect as it includes multicellular organisms, which do not fit the definition of single-celled organisms.
- Option 4 (None of these) is also incorrect because we have a valid option.

6. **Conclusion**: The correct answer is Option 1: Unicellular.

**Final Answer**: Single-celled organisms are called **unicellular**.

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