Question

1. a relationship between two organisms in which both organisms benefit.

mutualism
competition
parasitism
commensalism

Explanation:

Mutualism is a symbiotic relationship where both organisms benefit. Competition is when organisms vie for resources. Parasitism is one - organism - benefits - at - another's - expense. Commensalism is one - organism - benefits - and - the - other - is - unaffected.

Answer:

Mutualism