Final answer:
Exit row seats are the only seats on an airplane that passengers are not allowed to move from due to safety regulations and the responsibilities associated with these seats in case of an emergency evacuation.
Step-by-step explanation:
The exit row seats are the only ones that are not able to move to a different seat. Airlines have specific requirements determined by safety regulations for passengers who sit in the exit rows. These seats are in critical areas of the airplane, where passengers may be required to assist in the unlikely event of an emergency evacuation.
Therefore, to ensure safety, passengers sitting in exit row seats are selected based on their ability to perform evacuation actions, and are not allowed to move to other seats once they have agreed to the responsibilities that come with sitting in these seats. On the other hand, passengers in standard seats, upfront seats, and extra legroom seats usually have the flexibility to change seats, as these seats do not come with the same safety requirements and responsibilities.