In which one of the following functions, white muscles are not used ?

Options

A. Moving of eye balls
B. Fast and strenous work for short duration
C. For sustained work at a slow rate for a prolonged duration
D. Fast flights as in sparrows

Answer

To determine in which function white muscles are not used, we first need to understand the characteristics of white muscles compared to red muscles.

### Step-by-Step Solution:

1. **Understanding Muscle Types**:
- There are two main types of muscles in humans: red muscles and white muscles.
- Red muscles are rich in capillaries, contain myoglobin, and have a large number of mitochondria. They are suited for endurance and prolonged activities.
- White muscles, on the other hand, have fewer capillaries and mitochondria, making them less efficient for long-duration activities. They are primarily used for quick, short bursts of activity.

2. **Analyzing the Options**:
- **Option 1: Moving of Eyeball**: This activity requires quick movements but lasts only for a short duration. White muscles can perform this function, so this option is incorrect.
- **Option 2: Fast and Strenuous Work for Short Duration**: White muscles are well-suited for this type of activity as they can generate quick bursts of strength. Therefore, this option is also incorrect.
- **Option 3: Sustained Work at Slow Rate for Prolonged Duration**: White muscles are not designed for prolonged activities. They fatigue quickly and are not suitable for sustained work over a long period. This option is correct.
- **Option 4: Fast Flight as in Sparrows**: This is another example of a short-duration activity where white muscles can be effectively used. Hence, this option is incorrect.

3. **Conclusion**:
- The correct answer is **Option 3: Sustained Work at Slow Rate for Prolonged Duration**, as white muscles are not used for this function.