Select the word that best defines the italicized word. wane sick healthy increase decrease

decrease

Explanation:

The verb to wane means to diminish in intensity, to be less brilliant or powerful, a bit like a to dim. So, decrease would be the best match to wane. You might have a dimmer control at home for some lights, to control the intensity.

Increase is the opposite of to increase of course.

Healthy and sick are not words that have similar meanings as wane, since they relate to living organisms, not lights.