Answer:
mutualistic relationship.
paraquat is a herbicide.
Diuron is a algaecide.
Explanation:
mutualistic relationship is present between coral and algae. Paraquat did not cause the coral bleaching because paraquat is a herbicide which is used to kill weeds not algae. We know that coral have small algae attached to its body which is responsible for its colour so if we apply paraquat, it does not kill the algae and so coral bleaching did not occur. if we apply diuron which kills algae so it causes coral bleaching and the coral becomes white.