After Some Time,the Tip of a Plant That Has Been

Multiple Choice

After some time,the tip of a plant that has been forced into a horizontal position grows upward.This phenomenon is related to

A) calcium release from the endoplasmic reticulum of shaded cells.
B) whether the plant is in the northern or southern hemisphere.
C) auxin production in cells receiving red light.
D) auxin movement toward the lower side of the stem.