Which simple action is useful for making a small flower petal with a brush?

Correct answer: Pressing the brush and lifting it with a slight turn

The governing concept is the press-and-lift brush stroke, in which pressure controls the width and lifting reduces the mark to a pointed end. A slight turn can help shape the curved form of a small petal. Therefore option A is correct. Leaving the brush in water does not create a mark, rubbing may damage the paper, and the handle cannot apply paint with fine control.