Human-powered transport remains popular for reasons of cost-saving, leisure, physical exercise, and environmentalism. Human-powered transport is sometimes the only type available, especially in underdeveloped or unreachable regions. It is considered an ideal form of transportation. ———According to the passage, which is NOT the reason for the popularity of human-powered transport?
A.
Human-powered transport can save costs.
B.
Human-powered transport is a kind of physical exercise.
C.
Human-powered transport is beneficial to environmental protection.
D.
Human-powered transport is the only form of transportation in unreachable