*Question E7A10:
What is a truth table?*  

*Correct Answer is  B: A list of inputs and corresponding outputs for a digital device*  

### AI Response: (may contain errors)  

A truth table is a systematic way to represent the relationship between the inputs and outputs of a digital device, such as logic gates or circuits. 

### Correct Answer Explanation:
- **B: A list of inputs and corresponding outputs for a digital device** is correct because a truth table explicitly shows all possible combinations of input values and the resulting output for a digital circuit. Each row of the table corresponds to a unique combination of inputs, and the output is determined based on the logic of the device.

### Incorrect Answer Explanations:
- **A: A list of inputs and corresponding outputs for an op-amp** is incorrect because truth tables are not typically used for operational amplifiers (op-amps), which are analog devices. Op-amps operate on continuous signals rather than discrete logic levels.
  
- **C: A diagram showing logic states when the digital gate output is true** is incorrect because a truth table is not a diagram; it is a tabular representation. While it does show outputs for various input states, it does not visually represent them as a diagram would.

- **D: A table of logic symbols that indicate the logic states of an op-amp** is incorrect because truth tables do not include logic symbols. They focus on input-output relationships rather than symbol representation.

### Useful Rules of Thumb:
- A truth table typically has $2^n$ rows, where $n$ is the number of input variables. This accounts for all possible combinations of binary inputs (0 and 1).
- Each output in the truth table is determined by the logical operation performed by the device (AND, OR, NOT, etc.).

In summary, a truth table is essential for understanding how digital devices respond to various inputs, making it a fundamental concept in digital electronics.