When stated as a percentage, the useful energy transferred by a device divided by the total energy supplied to the device is known as the device's what one word completes the sentence?

Aswimmer is determined to cross a river that flows due south with a strong current. initially, the swimmer is on the west bank desiring to reach a camp directly across the river on the opposite bank. in which direction shoud the swimmer head? a. the swimmer should swim southeast. b. the swimmer should swim south. c. the swimmer shuold swim northeast. d. the swimmer should swim due north. e. the swimmer should swim due east.