Gravitropism in plant shoots and roots differ in that A) only ...

[xclash]

Gravitropism in plant shoots and roots differ in that
A) only shoots depend upon auxin distribution.
B) only shoots depend upon the aggregation of statoliths.
C) only roots exhibit rapid elongation of specific cells.
D) only roots sense gravity at the tips.
E) the threshold and response time is much less in shoots than in roots.

[clippers!]

I chose E and got the answer, hope that helps.