Statement: An announcement: Passengers in their own interest are advised to fasten their seat belts while seated in the trolley of the ropeway.
Assumptions:
1. People are always careful about their own safety.
2. Unless advised, passengers might not use the seat belts.
Answer: E
The stress on 'in their own interest' in the statement indicates that people should use seat belts for their own safety. So, I is implicit. Besides, the announcement has been made to caution passengers to be careful if they want to enjoy a safe ride. So, II is also implicit.