Why is his family very fond of family travelling?

A、It is exciting to meet and make friends with people of different colors and races.
B、It is one of the best ways to know the customs and living habits of the local people.
C、When they return from their trip, they generally feel fresh and energetic, ready to work harder.
D、It is exciting to visit different places and to know the customs of the local people, and travelling is one of the best ways to learn.