"Heat cannot by itself flow from a body at lower temperature to a body at higher temperature" is a statement or consequence of

Options

A. second law of thermodynamics
B. conservation of momentum
C. conservation of mass
D. first law of thermodynamics

Explanation

To solve the question "Heat cannot by itself flow from a body at lower temperature to a body at higher temperature" is a statement or consequence of:

### Step-by-step Solution:

1. **Understanding Heat Transfer**:
- Heat transfer occurs from a region of higher temperature to a region of lower temperature. This is a fundamental observation in thermodynamics.

2. **Introducing the Second Law of Thermodynamics**:
- The second law of thermodynamics states that in any energy exchange, if no energy enters or leaves the system, the potential energy of the state will always be less than that of the initial state. This law introduces the concept of entropy.

3. **Defining Entropy**:
- Entropy is a measure of the disorder or randomness of a system. According to the second law, the total entropy of an isolated system can never decrease over time. It either increases or remains constant.

4. **Analyzing the Statement**:
- The statement "Heat cannot by itself flow from a body at lower temperature to a body at higher temperature" implies that if heat were to flow from a colder body to a hotter body, the entropy of the system would decrease, which contradicts the second law of thermodynamics.

5. **Conclusion**:
- Therefore, the statement is a consequence of the second law of thermodynamics, which asserts that heat cannot spontaneously flow from a colder object to a hotter object because it would lead to a decrease in the total entropy of the system.

### Final Answer:
The statement "Heat cannot by itself flow from a body at lower temperature to a body at higher temperature" is a consequence of the **Second Law of Thermodynamics**.