Most biologists believe that

a. there are more commensal relationships than we think

b. there are no true parasitic relationships in nature

c. animals are probably harmed or by commensalism in subtle ways

d. animals most likely benefit from parasitic relationships in unknown ways

B.) There are no true parasitic relationships in nature:

Most biologists believe there are no true parasitic relationships in nature, rather the idea that true commensalism does not exist. Commensalism is a symbiotic interaction in which species benefit from the association while neither benefit or harm each other.

answer; /// i believe that the correct answer is(

answer; i believe that the correct answer is (d); // supercontinent