Which one refers to allen's rule

Options

A. If stressful conditions are localised, an organism either migrates or suspends itself
B. Mammals from colder climates have shorter ears and limbs to minimise heat loss
C. An organism can move from a stressful habitat to a mare hospitable area and return when the stressful period is over
D. Low atmospheric pressure in higher altitudes results in altitude sickness.

Answer

**Step-by-Step Solution:**

1. **Understanding Allen's Rule**: Allen's Rule states that endothermic (warm-blooded) animals tend to have shorter limbs and body parts in colder climates compared to those in warmer climates. This adaptation helps minimize heat loss.

2. **Analyzing the Options**: The question provides several options. We need to identify which one aligns with Allen's Rule:
- Option 1: If stressful conditions are localized, an organism either migrates or suspends itself.
- Option 2: Mammals from colder climates have shorter ears and limbs to minimize heat loss.
- Option 3: An organism can move from a stressful habitat to a more hospitable area and return when the stressful period is over.
- Option 4: Low atmospheric pressure in higher altitudes results in altitude sickness.

3. **Identifying the Correct Option**: Among the options, Option 2 directly describes the principle of Allen's Rule, as it specifically mentions mammals from colder climates having shorter ears and limbs to minimize heat loss.

4. **Conclusion**: Therefore, the correct answer to the question "Which one refers to Allen's rule?" is:
- **Mammals from colder climates have shorter ears and limbs to minimize heat loss.**

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