What is the relationship between piperonyl butoxide and pyrethrum insecticide?
a) Piperonyl butoxide is not an insecticide on its own but can enhance the effects of pyrethrum insecticide.
b) The addition of piperonyl butoxide to a pyrethrum insecticide can greatly increase its effectiveness.
c) Piperonyl butoxide acts as an antagonist, enhancing the effects of pyrethrum insecticide in a phenomenon known as antagonism.
d) When combined with pyrethrum insecticide, piperonyl butoxide can be called an antagonist, leading to increased insecticidal activity.