Final answer:
The correct step for a passenger with a disability to change seats according to the Air Carrier Access Act is to notify the gate agent, who will accommodate their needs while complying with regulations.
Step-by-step explanation:
When a passenger with a disability needs to change seats, the correct protocol under the Air Carrier Access Act (ACAA) is B) Notifying the gate agent. The gate agent is responsible for ensuring passengers' needs are accommodated in accordance with ACAA regulations. Contacting cabin crew might be helpful once onboard for immediate adjustments, but the primary action should be taken before boarding by informing the gate agent. Passengers themselves are not responsible for making seat changes independently or notifying fellow passengers about their disability or needs for seat changes.
It is important for passengers with disabilities to communicate their needs as early as possible, preferably during the booking process or at least 48 hours in advance of their flight. This allows the airline adequate time to make the necessary arrangements to ensure the passenger's comfort and safety during the flight.