To protect itself from herbivores, plants
a)cannot do anything because they cannot protect themselves
b)both secure toxins and have thorns
c)secrete toxins
d)have thorns

B) both secrete toxins and have thorns

Plants undergoes several adaptations in order to survive in their environment and to defend themselves from the herbivores. The presence of thorns on the surface of the plants is a structural adaptation, these thorns will get inserted in the herbivores and will discourage their feeding on the plants. They secrete toxins to the external surface, it is physiological adaptation, which can kill the herbivores and also discourage other members from feeding.

synapse nervous system