Question

A sudden change in the external or internal environment that results in a change in the activities of an organism is known as ______.

• A. stimulus
• B. impulse
• C. receptor
• D. effector

Answer 1

The correct option is A stimulus

Stimulus is something that causes a reaction. A stimulus can be internal or external. Sense organs, such as the ear, and sensory receptors, such as those in the skin, are sensitive to external stimuli such as sound and touch.