The Evidence That Some Beetles Cut Veins of Milkweeds to Interrupt

The evidence that some beetles cut veins of milkweeds to interrupt the flow of latex to other parts of the plant demonstrates that

A) laticifers are always effective as plant defenses.
B) laticifers are always ineffective as plant defenses.
C) these beetles have learned to bypass an effective plant defense.
D) these beetles are able to overcome the toxicity of chemicals in latex.
E) milkweeds are unable to protect themselves from their own poisons.