Work Step by Step
The nervous system responds to external stimuli. Sensory information from the external environment are picked up by sense organs such as the skin, eyes, ears, nose, and mouth. The information then enters the nervous system. The nervous system then processes this information and decides what to do. This system comes into play when you touch a hot surface and immediately withdraw your finger. The other options are incorrect because they all involve the use of hormones, which are part of the endocrine system.