It Was Discovered Recently That Both Auxin and Gibberellins Have

It was discovered recently that both auxin and gibberellins have specific protein receptors that, when bound by hormones,

A) inactivate certain gene repressors in the nucleus.
B) activate certain gene repressors in the nucleus.
C) initiate a protein kinase cascade.
D) activate proton pumps in the plasma membrane.
E) acidify the cell wall.