Conservation of energy take place by :

Options

A. Sympathetic nervous system
B. Parasympathetic nervous system
C. Reflex action
D. None

Answer

To solve the question "Conservation of energy takes place by:", we will analyze the options provided and determine which one is correct based on the principles of biology and the functioning of the nervous system.

### Step-by-Step Solution:

1. **Understand the Concept of Energy Conservation**:
- Energy conservation in biological systems refers to the mechanisms that help maintain energy balance and reduce energy expenditure during various physiological states.

2. **Evaluate the First Option: Sympathetic Nervous System**:
- The sympathetic nervous system is responsible for the 'fight or flight' response. It increases heart rate, blood pressure, and energy expenditure during stressful situations.
- **Conclusion**: This option does not promote conservation of energy; hence, it is incorrect.

3. **Evaluate the Second Option: Parasympathetic Nervous System**:
- The parasympathetic nervous system is known for its role in 'rest and digest' functions. It helps to decrease heart rate and promote relaxation, which conserves energy.
- **Conclusion**: This option correctly represents the conservation of energy.

4. **Evaluate the Third Option: Reflex Action**:
- Reflex actions are involuntary responses to stimuli that occur quickly and do not involve conscious thought. While they are important for survival, they do not specifically relate to energy conservation.
- **Conclusion**: This option is incorrect as it does not focus on energy conservation.

5. **Evaluate the Fourth Option: None**:
- This option suggests that none of the previous options are correct. However, we have established that the parasympathetic nervous system does promote energy conservation.
- **Conclusion**: This option is also incorrect.

### Final Answer:
The correct answer is **Parasympathetic Nervous System**, as it is the system that promotes relaxation and conservation of energy in the body.

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