(A): Unlike electrostatic field the lines of induced field from closed loop.
(R): Electrostatic field is conservative unlike induced fields.

Options

A. Both A and R are true and R is the correct explanation
B. Both A and R are true but R is not the correct explanation of A
C. A is true but R is false
D. Both A and R are false

Answer

To solve the given question, we need to analyze both the assertion (A) and the reason (R) provided in the statement.

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that "unlike electrostatic field, the lines of induced field form closed loops."
- In electromagnetic induction, when a magnetic field changes, it induces an electric field. This induced electric field is characterized by its lines forming closed loops.

2. **Understanding the Reason (R)**:
- The reason states that "electrostatic field is conservative unlike induced fields."
- A conservative field is one where the work done in moving a charge between two points is independent of the path taken. In electrostatics, the electric field is conservative, meaning that the work done around a closed path is zero.

3. **Analyzing the Assertion**:
- The assertion is true because the induced electric field indeed forms closed loops. This is a fundamental concept in electromagnetism, where the induced electric field is related to the change in magnetic flux through a loop.

4. **Analyzing the Reason**:
- The reason is also true. The electrostatic field is conservative, which means that the work done in moving a charge in an electrostatic field around a closed loop is zero. This property distinguishes it from the induced electric field.

5. **Relationship Between Assertion and Reason**:
- The reason explains why the assertion is true. Since the induced electric field is non-conservative (it forms closed loops), it is fundamentally different from the electrostatic field, which is conservative.

6. **Conclusion**:
- Both the assertion (A) and the reason (R) are true, and the reason correctly explains the assertion. Therefore, the correct answer is that both A and R are true, and R is a correct explanation of A.

### Final Answer:
Both A and R are true, and R is a correct explanation of A.