A relationship in which one species is helped and the other is NOT harmed.
A. Mutualism

B. Parasitism

C. Commensalism

D. Predation

c

Explanation:

a = both benefit

b one benefit and one harm

c = one benefit and one isnt affected

C. commensalism

Explanation:  Commensalism is an association between two organisms in which one benefits and the other derives neither benefit nor harm while mutualism is symbiosis that is beneficial to both organisms involved and parasitism is  symbiotic relationship between species, where one organism, the parasite, lives on or in another organism, the host, causing it some harm, and is adapted structurally to this way of life.