*Question E7A07:
What logical operation does a NAND gate perform?*  

*Correct Answer is  D: It produces a 0 at its output only if all inputs are 1*  

### AI Response: (may contain errors)  

A NAND gate is a fundamental digital logic gate that performs a specific logical operation. 

### Correct Answer Explanation:
- **Correct Answer (D)**: A NAND gate produces a 0 at its output only if all inputs are 1. This means that the output is 1 in all other cases (when at least one input is 0). 

### Truth Table for NAND Gate:
Here’s a truth table that illustrates the behavior of a NAND gate:

| Input A | Input B | Output (A NAND B) |
|---------|---------|-------------------|
|    0    |    0    |         1         |
|    0    |    1    |         1         |
|    1    |    0    |         1         |
|    1    |    1    |         0         |

From the truth table, you can see that the output is 0 only when both inputs are 1.

### Why Other Choices Are Incorrect:
- **Choice A**: It produces a 0 at its output only if all inputs are 0.  
  - **Incorrect**: This describes a NOR gate, not a NAND gate. A NAND gate outputs 1 when at least one input is 0.

- **Choice B**: It produces a 1 at its output only if all inputs are 1.  
  - **Incorrect**: This describes an AND gate. A NAND gate outputs 0 only when all inputs are 1, not 1.

- **Choice C**: It produces a 0 at its output if some but not all inputs are 1.  
  - **Incorrect**: This is not true for a NAND gate. It outputs 1 if at least one input is 0, regardless of the state of the other inputs.

### Summary:
- A NAND gate outputs 0 only when all inputs are 1.
- It outputs 1 in all other cases.
- Remember the truth table for quick reference during the exam. 

This understanding of NAND gates is crucial for digital electronics and will help you in various applications, including circuit design and troubleshooting.