Why Do Plants That Grow in Windows Grow at an Angle

Why do plants that grow in windows grow at an angle unless rotated?

A) Cells on the sunny side of the stem lose more water than those on the dark side,making the plant bend.
B) Cells on the stem's darker side stretch out as auxin collects there,causing the stem to bend.
C) Rising levels of auxin on the stem's sunny side cause cells to shrink,tilting the stem toward the light.
D) Auxin collects on the sunny side and gibberellin on the dark side of the stem,making the stem grow unevenly.
E) Gibberellin builds up on the dark side of the stem,prompting cell division,which elongates the dark side.