Question

Which part of the nervous system is the first to work when Joshue feels a raindrop fall on his arm? brain spinal cord sensory neuron motor neuron

Answer 1

The sensory neuron.

As you can tell from the name. "sensory" means something you can sense. Smell, taste, Etc...  The neuron is in charge of taking these things to your brain

Answer 2

The right answer is the sensory neuron.

The sensory neuron, or sensory neuron, is a neuron located in a sensory ganglion that plays a role in the perception of a stimulus. Sensory neurons are often referred to as "afferent fibers". For example, a sensory neuron can be used for the perception of heat, or contact with an object.