Final answer:
Option A) parasite is an organism that lives in or on another organism and derives nutrients from it. The parasite benefits while the host is harmed. Parasites are unlikely to kill the host quickly to allow completion of their reproductive cycle.
Step-by-step explanation:
A parasite is an organism that lives in or on another living organism and derives nutrients from it(option a). The parasite benefits from this relationship, while the host is harmed. The host is usually weakened as the parasite siphons resources that the host would normally use for its own maintenance.
Parasites are unlikely to kill the host quickly, as this would prevent the parasite from completing its reproductive cycle. Examples of parasites include fleas, ticks, and tapeworms.