Which of the following is a symptom of motion sickness?

Excessive salivation is a symptom commonly associated with motion sickness. This condition arises when there is a discrepancy between the signals that the body receives from the inner ear, eyes, and deeper body parts regarding movement and balance. In the case of motion sickness, the brain receives conflicting messages, which can lead to various physical responses, one of which is increased salivation. This occurs as the body anticipates nausea and prepares for potential vomiting.

Motion sickness symptoms often include nausea, vomiting, dizziness, and excessive salivation as the body reacts to the confusion caused by motion. The other options listed do not typically relate to motion sickness. Weight loss usually results from chronic conditions or prolonged illness, broken blood vessels in the eyes can occur from various causes but are not a primary symptom of motion sickness, and thinning hair is associated with a range of other issues unrelated to motion and balance. Therefore, excessive salivation stands out as a direct and relevant symptom of motion sickness.