Final answer:
The correct option is b. The lights on during pre-arrival service in the main cabin are typically blue lights. These lights are usually dimmed to help passengers adjust their eyes to the outside light after a long flight.
Step-by-step explanation:
The lights on during pre-arrival service in the main cabin can vary depending on the airline and specific procedures followed, but typically, blue lights are used.
Blue lights help create a relaxing and calming atmosphere for passengers during the landing process. These lights are usually dimmed to help passengers adjust their eyes to the outside light after a long flight.