Several Plants,including the Castor Oil Plant,defend Themselves Against Herbivory by Producing

Several plants,including the castor oil plant,defend themselves against herbivory by producing highly toxic water-soluble proteins called ricins.Proricin,consisting of A and B chains,is stored in vacuoles called protein bodies.It becomes active when an enzyme inside the protein body cleaves the A and B chains.This suggests that the castor oil plant is able to avoid self-poisoning by

A) compartmentalizing the ricins.
B) storing the ricins on the plant surface.
C) storing the ricins in the plasma membrane.
D) both compartmentalizing the ricins and storing them as precursors.
E) both storing the ricins in the plasma membrane and storing them as precursors.