Question

which sentence uses this meaning of dial?
dial noun a knob on an electronic device
if you have any questions, dial the number at the bottom of the screen.
which dial do i turn to sharpen the image on the screen?

Explanation:

We need to find the sentence where "dial" is used as a noun meaning "a knob on an electronic device". In the first sentence, "dial" is a verb (to call by entering a number). In the second sentence, "dial" is a noun referring to the knob on a device (to sharpen the image, you turn the dial).

Answer:

Which dial do I turn to sharpen the image on the screen?