Assertion: Electromagnets are made of soft iron.
Reason: Coercivity of soft iron is small.

Options

A. Assertion is correct, reason is correct, reason is a correct explanation for assertion.
B. Assertion is correct, reason is correct, reason is not a correct explanation for assertion
C. Assertion is correct, reason is incorrect
D. Assertion is incorrect, reason is correct

Explanation

To solve the question, we need to analyze the assertion and reason provided:

**Assertion:** Electromagnets are made of soft iron.
**Reason:** Coercivity of soft iron is small.

### Step-by-Step Solution:

1. **Understanding Electromagnets:**
- Electromagnets are devices that use electric current to generate a magnetic field. They are designed to be easily turned on and off, which requires a material that can be magnetized and demagnetized quickly.

2. **Properties of Soft Iron:**
- Soft iron is a type of ferromagnetic material that is characterized by its ability to be magnetized easily and to lose its magnetism quickly when the external magnetic field is removed. This property is crucial for the functioning of electromagnets.

3. **Coercivity:**
- Coercivity is a measure of the resistance of a magnetic material to becoming demagnetized. A material with low coercivity can be easily demagnetized, which is desirable for electromagnets that need to switch states frequently.

4. **Hysteresis Loss:**
- When a magnetic material is magnetized and demagnetized, there is a loss of energy due to the hysteresis effect. Soft iron has a lower hysteresis loss compared to hard magnetic materials, making it more efficient for use in electromagnets.

5. **Conclusion:**
- Since electromagnets require materials that can be magnetized and demagnetized easily, soft iron is chosen due to its low coercivity and minimal hysteresis loss. Thus, both the assertion and the reason are true, and the reason correctly explains why the assertion is true.

### Final Answer:
Both the assertion and the reason are true, and the reason is a correct explanation of the assertion.

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