Functional unit of muscle is :

Options

A. Fasciculi
B. Muscle fibre
C. Bundle
D. Both (a) and (c )

Answer

To determine the functional unit of muscle, we can analyze the options provided in the question step by step.

### Step-by-Step Solution:

1. **Understanding the Structure of Muscle**:
- Muscles are made up of various components, and understanding these components is crucial to identifying the functional unit.

2. **Analyzing the First Option - Fasciculi**:
- Fasciculi are bundles of muscle fibers. Each fasciculus is surrounded by a layer of connective tissue called perimysium. This indicates that fasciculi play a significant role in muscle structure.

3. **Analyzing the Second Option - Muscle Fiber**:
- Muscle fibers are the individual cells that make up the fasciculi. While they are essential for muscle function, they are not considered the functional unit of the muscle as a whole.

4. **Analyzing the Third Option - Bundle**:
- The term "bundle" can refer to fasciculi, which are indeed bundles of muscle fibers. This option is somewhat redundant as it relates back to the first option.

5. **Analyzing the Fourth Option - Both A and C**:
- Since both fasciculi (option A) and the concept of a bundle (option C) are correct in the context of muscle structure, this option encompasses both correct answers.

### Conclusion:
The correct answer to the question "Functional unit of muscle is:" is **option 4 - both A and C**. This is because fasciculi (bundles of muscle fibers) serve as the functional unit of muscle.