Which term indicates the ability of an organism to respond to stimuli in its environment?

The term that signifies an organism's ability to respond to stimuli in its environment is responsiveness. This concept encompasses how organisms detect changes in their surroundings (stimuli) and the various ways they react to those changes. Responsiveness is a fundamental characteristic of life, as it allows organisms to interact with their environment and modify their behavior or physiological processes based on external conditions.

Reactivity is a related term, but it is often used in different contexts, such as describing how substances interact chemically. Homeostasis refers to the ability of an organism to maintain stable internal conditions, and adaptability pertains to the ability of an organism to change over time in response to environmental pressures, which is a broader concept related to evolutionary changes rather than immediate responses to stimuli. Therefore, responsiveness is the most precise term that captures the immediate reaction of organisms to their environment.