Plant Primary Roots Typically Grow into the Ground by Responding

Plant primary roots typically grow into the ground by responding to the directional signal of gravity.If you wanted to identify a plant that had a mutation in its gravity signal transduction pathway, which of the following methods would be most useful?

A) Growing a batch of seeds in zero-gravity conditions and then collecting any seedlings with primary roots that are growing in different directions
B) Treating a batch of seeds with a mutagen, placing each germinating seed on the soil with the primary roots emerging in a different direction, and collecting any plants with primary roots that grow into the soil
C) Treating a batch of seeds with a mutagen, growing them alongside wild-type seeds, and collecting any seedlings with primary roots growing longer than the wild-type roots
D) Growing a batch of seeds in zero-gravity conditions and then collecting any seedlings with primary roots that are growing toward the ground
E) Treating a batch of seeds with a mutagen, growing them alongside wild-type seeds, and collecting any seedlings with primary roots growing in a direction that is different from that of the wild-type roots