<span>Anything in an organism's environment that causes it to react is called a STIMULUS. A stimulus is defined as an impulse that evokes a specific functional response from an organism. In living organisms, stimulus can occur both internally and externally. Stimulus generate appropriate response in living organisms. Thus, the correct option is C.</span>
What I know is that sickle-cell anemia is when red blood cells are sickle-shaped instead of disc-shaped and can't deliver enough oxygen to the cells in the body.
