Which of the following symptoms is particularly severe in motion sickness during flight?

Nausea is particularly severe in motion sickness during flight because it is a primary symptom that arises from the conflict between sensory inputs. During flight, the inner ear detects changes in motion while visual cues from the environment may not align with those sensations, leading to confusion in the brain. This sensory mismatch is a key factor contributing to motion sickness, causing reactions such as nausea.

While dizziness, headache, and fatigue can also occur with motion sickness, nausea tends to be the most pronounced and debilitating symptom for many individuals. It is significant because it directly impacts a person's ability to continue flying or perform other tasks, highlighting the importance of understanding and managing this symptom in aviation contexts.