Which systems does a taser primarily affect?

A taser primarily affects the sensory nervous system and motor functions, which is why this choice is the correct one. When a taser is deployed, it emits an electrical charge designed to disrupt the body's neuromuscular control, impacting the way the brain communicates with the muscles. This leads to immediate loss of motor control, causing temporary incapacitation.

The sensory nervous system is affected as well, as the electrical impulses can create sensations such as pain or discomfort, alerting the individual to the taser's effects. This interaction between sensory feedback and motor response is critical to understanding how a taser incapacitation works.

In contrast, the other options touch on systems that are not directly impacted by a taser. The respiratory and cardiovascular systems may experience secondary effects due to stress or incapacitation but are not the primary targets. The digestive system and immune response do not play a role in the immediate effects of a taser, nor does the endocrine system and metabolic rate, which are not influenced by the electric shock in the way that motor and sensory functions are directly affected.