Which case below best represents a case of price$$ discrimination?

A$.$

A utility company charges less for electricity used during$$ "off$-$peak" hours, when it does not have to operate its$$ less$-$efficient generating plants.

B$.$

A major airline sells tickets to senior citizens at lower prices than to other passengers.

C$.$

An insurance company offers discounts to safe drivers.

D$.$

A professional baseball team pays two players with different batting averages different salaries.