Parasite is defined as

• A. Any animal or plant that lives on and feeds on another animal or plant
• B. A Beneficial Partner That Helps Host
• C. A Virus That Infects Cells
• D. A Predator That Hunts Prey

Answer: (A)

Parasite describes an organism that lives on or inside another organism (the host) and derives nutrients from it, usually at the host’s expense. The description that fits this idea is the one that talks about an organism—whether animal or plant—that lives on and feeds on another organism. This captures the ongoing, dependent relationship typical of parasitism. The other options describe different relationships: a beneficial partner hints at mutualism, a virus is a separate category of parasite of cells but isn’t framed here as a plant or animal, and a predator is about active hunting and killing, not living on or feeding off a host over time.