C
Below is a question with multiple-choice answers. Choose the correct option based on your reasoning.

### Question:
When a button is pushed on a battery-operated clock, the time display is illuminated. What process has taken place?

### Choices:
A. Pressure has been converted to light.
B. Force has been converted to light.
C. Closing an electric circuit has produced light.
D. Opening an electric circuit has produced light.

### Answer:
