When a muscle bends one part upon the other, it is called

Options

A. 1)abductor
B. 2)adduction
C. 3)extensor
D. 4)flexor

Answer

To answer the question "When a muscle bends one part upon the other, it is called," we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for the term used to describe a muscle action that involves bending one part of the body upon another.

2. **Analyze the Options**: We have four options to consider:
- A) Abductors
- B) Adduction
- C) Extensor
- D) Flexor

3. **Define Each Option**:
- **Abductors**: These muscles move a limb away from the midline of the body. Therefore, they do not fit the description of bending one part upon another.
- **Adduction**: This term refers to the movement of a limb toward the midline of the body. Again, this does not describe the action of bending.
- **Extensor**: An extensor muscle straightens a limb or part of the body. This is the opposite of bending.
- **Flexor**: A flexor muscle is responsible for bending a part of the body upon another part. This matches the description given in the question.

4. **Select the Correct Option**: Based on the definitions, the correct answer is **D) Flexor**, as it specifically refers to the muscle action of bending one part upon another.

5. **Conclusion**: Therefore, when a muscle bends one part upon the other, it is called a flexor.

### Final Answer:
The correct answer is **D) Flexor**.