Several Scientists, Including Charles and Francis Darwin, Frits Went and Others

Several scientists, including Charles and Francis Darwin, Frits Went and others, demonstrated that auxins caused stems to bend toward light in a series of elaborate experiments. Went was the researcher who finally determined that bending of the stem toward light was a result of which mechanism?

A) Light caused a reduction in auxin concentration and a reduction in stem elongation on the lighted side of the plant stem, and thus a bending in the direction of the light.
B) The transport of auxin to the shaded side of the plant stem stimulated stem elongation and a bending in the direction of the light.
C) Auxin concentration was equal on both sides (lighted and shaded) of the stem; however, the apical meristem responded to the presence of light.
D) A combination of positive phototropism and a negative gravitropism.
E) The stems actually were responding to the agar blocks that had been used in the experiments.