Which physical activity component focuses on the speed of motor responses?

The component of physical activity that centers on the speed of motor responses is reaction time. This aspect of physical fitness measures how quickly a person can respond to a stimulus, which is crucial in many sports and physical activities. When an athlete reacts to an unexpected event, such as a starting gun in a race or a ball being thrown, effective and quick motor responses are essential for performance.

In contrast, coordination involves the ability to use different parts of the body together smoothly and efficiently, which is vital for tasks that require precise movements but does not specifically focus on speed. Flexibility refers to the range of motion in joints and muscles, contributing to overall physical performance but not directly related to the quickness of responses. Agility is the ability to change direction quickly and control body movements, which, while related to speed, does not directly measure the speed of responding to a stimulus like reaction time does. Thus, reaction time is distinctly focused on the rapidity of motor responses, making it the correct choice.