Which of the following is an example of how emotions can affect the body?

When individuals experience strong emotions, such as fear, excitement, or anxiety, their bodies often respond physiologically. An increased pulse rate is a common reaction, as the body's sympathetic nervous system kicks in, preparing for a "fight or flight" response. This change is due to the release of adrenaline and other stress hormones, which increase heart rate to pump more blood and oxygen to essential organs and muscles, enhancing physical capacity to react to a situation.

The other options, while they may represent reactions to various stimuli, do not specifically illustrate the direct physiological effects emotions have on the body in the same way an increased pulse rate does. Narrowed focus and changes in visual perception can occur under certain emotional states, but they don't involve the same straightforward physiological changes that increased heart rate does. Color blindness, on the other hand, is a visual deficiency unrelated to emotional responses.