Which of the following describes predation?

Predation is defined as an interaction in which one organism, the predator, kills another organism, the prey, for food. In this relationship, the predator benefits because it obtains nourishment that is essential for its survival, while the prey is harmed as it is killed in the process. This dynamic is crucial in ecological systems, as it helps regulate populations of different species and maintain balance within ecosystems.

The other definitions do not encapsulate the essence of predation's primary characteristic, which is the act of one organism killing another. An organism living on or in another organism describes parasitism, while mutualism refers to interactions where both organisms benefit. Finally, the description of one organism being neither helped nor harmed typically refers to commensalism, which is different from the predatory relationship where one organism's survival depends on harming another. Thus, the correct choice underscores the fundamental nature of predation as a critical ecological interaction.