It is much easier for a small animal to run uphill than for a large animal,because

Options

A. Small animals have a lower `O_2` requirement
B. The efficiency of muscles in large animals is less than in the small animal
C. II is easier to carry a small body weight
D. Smaller animals have a higher metabolic rate

Answer

**Step-by-Step Solution:**

1. **Understanding the Question:**
The question asks why small animals find it easier to run uphill compared to larger animals.

2. **Analyzing the Options:**
The options provided are:
- A) Small animals have lower oxygen requirements.
- B) The efficiency of muscles in larger animals is less than in small animals.
- C) It is easier to carry a small body weight.
- D) Small animals have a higher metabolic rate.

3. **Evaluating Each Option:**
- **Option A:** This statement is incorrect. While small animals may have lower overall oxygen requirements at rest, during strenuous activities like running uphill, their oxygen requirements increase.
- **Option B:** This statement is also incorrect. Larger animals do not necessarily have less efficient muscles; muscle efficiency can vary based on many factors, including type and conditioning.
- **Option C:** This statement is partially correct. While it is true that smaller animals have less body weight to carry, this does not fully explain why they can run uphill more easily.
- **Option D:** This statement is correct. Small animals typically have a higher metabolic rate, which means they can generate energy more quickly to support strenuous activities like running uphill.

4. **Conclusion:**
The most logical reason why small animals find it easier to run uphill is that they have a higher metabolic rate (Option D). This higher metabolic rate allows them to utilize energy more efficiently during physical exertion.

5. **Final Answer:**
Therefore, the correct answer is **D) Small animals have a higher metabolic rate.**

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