Which of the following gives a reversible operation ?

Options

A.
B.
C.
D.

Explanation

To determine which of the given options represents a reversible operation, we need to analyze each option based on the principles of logic gates and their outputs. A reversible operation means that for every output, there is a unique input that can produce it.

### Step-by-Step Solution:

1. **Understand Reversible Operations**:
- A reversible operation is one where the output can uniquely determine the input. For example, if you input A and get output B, you should be able to input B and get back A.

2. **Analyze Option A (NOR Gate)**:
- A NOR gate takes two inputs A and B and outputs the negation of the OR operation. The output is true only when both inputs are false.
- The truth table shows that multiple input combinations can yield the same output, indicating that it is not reversible.

3. **Analyze Option B (AND Gate)**:
- An AND gate outputs true only if both inputs A and B are true.
- Similar to the NOR gate, multiple combinations of inputs can lead to the same output, hence it is not reversible.

4. **Analyze Option C (NAND Gate)**:
- A NAND gate outputs false only when both inputs A and B are true.
- Like the previous gates, it also does not provide a unique output for every input combination, indicating it is not reversible.

5. **Analyze Option D (OR Gate)**:
- An OR gate outputs true if at least one of the inputs A or B is true.
- Again, multiple input combinations can yield the same output, meaning it is not reversible.

6. **Conclusion**:
- After analyzing all options, it is clear that none of the gates (NOR, AND, NAND, OR) provide a reversible operation since they do not allow for unique determination of inputs from outputs.

### Final Answer:
None of the options (A, B, C, D) give a reversible operation.