A car rental costs $50 for the first day. Additional days cost $35 per day, unless the car is rented for 7 days or more, in which case there is a 10% discount on the daily rate.

Identify the expression which represents the cost of renting a car if the car has been rented for more than a week.
A) 45 + 35x
B) 45 + 31.5x
C) 50 + 35x
D) 50 + 31.5x​