Room prices are regularly $ 100, but for each additional room rented by a group, the price is reduced by $3 for each room. For example, 1 room costs $100, 2 rooms cost 2 × $97 = $ 194, 3 rooms cost 3 ×$ 94 = $282, and so on. What is the total cost of renting 6 rooms

A．the difference in bone structure reflects differences in their social roles
B．men appear to be braver than women partly because of biological reasons
C．men have a larger appetite than women do
D．men fall ill more often than women because of their deep breathing