What term refers to an organism that is fixed in one place and cannot move?

The correct term to refer to an organism that is fixed in one place and cannot move is "sessile." This term is commonly used in biology to describe organisms that are attached to a substrate, such as barnacles, sponges, and some types of corals. Sessile organisms do not have the ability to move from one location to another as they are anchored to a specific spot for their entire lives.

The choice "static" might suggest a lack of movement but does not specifically indicate that an organism is fixed in place as "sessile" does. "Mobile" and "motile," on the other hand, are terms that describe organisms capable of movement, further distinguishing them from sessile organisms. Understanding the unique characteristics of sessile organisms is critical when studying ecological roles, adaptations, and interactions with their environment.