Which description best outlines major ecological interactions such as predation, mutualism, commensalism, parasitism, and competition?

• A. Predation consumes; mutualism benefits both; commensalism benefits one; parasitism harms; competition for resources.
• B. Predation benefits both; mutualism harms one; commensalism harms both; parasitism benefits one.
• C. Competition for resources benefits the heterotroph.
• D. Mutualism harms the prey.

Answer: (A)

Ecological interactions describe how organisms affect each other's survival and reproduction. Predation is when one organism consumes another; mutualism is a relationship where both partners gain benefits; commensalism is when one partner benefits while the other is unaffected; parasitism is a relationship where the parasite benefits at the host’s expense; and competition occurs when organisms vie for the same limited resource, reducing fitness for those involved. The description that lays out these exact effects—predation consumes; mutualism benefits both; commensalism benefits one; parasitism harms; and competition for resources—fits how these interactions work in nature. The other options mix up these relationships (for example, claiming predation benefits both or commensalism harms both or mutualism harms the host) or imply an unusual outcome for competition, so they don’t align with how these interactions are defined.