Which of the following is a measure of an organism's responsiveness to environmental changes?

The measure of an organism's responsiveness to environmental changes is best represented by behavioral response. This term encompasses the various ways in which organisms react to stimuli in their surroundings. These responses can be immediate or involve more complex behaviors, such as migration, feeding, or mating behaviors, which are crucial for an organism's survival and reproduction.

Behavioral responses are especially important because they allow organisms to interact with their environment dynamically, adapting their actions based on immediate conditions. For example, an animal might find shelter in response to sudden rain, or a plant may grow toward a light source, demonstrating its behavioral adaptability to environmental changes.

Other options like adaptation, homeostasis, and survival also relate to how organisms respond to their environment, but they do so in different contexts. Adaptation refers to the long-term evolutionary process through which a species becomes better suited to its environment. Homeostasis involves the mechanisms that maintain internal stability in an organism despite external changes. Survival encompasses the broader concept of an organism's ability to live and reproduce in its environment, which is influenced by both behavioral responses and other factors. However, when focusing specifically on the immediate and varied ways an organism responds to environmental stimuli, behavioral response is the clearest measure.