The slow twitch muscle fibre which are rich in myoglobin and have abundant mitochondria are

Options

A. white skeletal muscles
B. cardiac muscles
C. red skeletal muscles
D. involuntary muscles.

Explanation

To answer the question about slow twitch muscle fibers that are rich in myoglobin and have abundant mitochondria, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Muscle Fiber Types**:
- Muscle fibers can be categorized into two main types: slow twitch (Type I) and fast twitch (Type II). Slow twitch fibers are known for their endurance and are used for prolonged activities.

2. **Characteristics of Slow Twitch Fibers**:
- Slow twitch muscle fibers are characterized by their high content of myoglobin, which is an oxygen-binding protein. This gives these fibers a reddish appearance.
- They also contain a high number of mitochondria, which are the powerhouses of the cell, responsible for aerobic respiration and energy production.

3. **Identifying the Muscle Types**:
- The question provides four options:
- A) White skeletal muscle
- B) Cardiac muscle
- C) Red skeletal muscle
- D) Involuntary muscles
- We need to identify which of these muscle types corresponds to the characteristics of slow twitch fibers.

4. **Analyzing the Options**:
- **White Skeletal Muscle**: These fibers are fast twitch and have low myoglobin content, thus they are not the answer.
- **Cardiac Muscle**: While cardiac muscle does have some similarities to slow twitch fibers, it is not classified as a slow twitch muscle fiber in the context of this question.
- **Red Skeletal Muscle**: These fibers are rich in myoglobin and have abundant mitochondria, making them suitable for aerobic activities. This matches the description of slow twitch fibers.
- **Involuntary Muscles**: This term generally refers to muscles that are not under conscious control, such as smooth muscles, which do not fit the description provided.

5. **Conclusion**:
- Based on the analysis, the correct answer is **C) Red skeletal muscle**, as these fibers are indeed rich in myoglobin and have abundant mitochondria, making them ideal for endurance activities.

### Final Answer:
The slow twitch muscle fibers which are rich in myoglobin and have abundant mitochondria are **C) Red skeletal muscle**.

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