jesse notices that his gas mileage jumps from 20 to 40 per gallon when he uses his cruise control. One likely explanation for this is:
a. jesse's car is powered by a biofuel that is not needed while cruising
b. jesse's car is compressing and expanding efficiently
c. jesse's car has an efficient air-to-fuel ratio
d. jesse's car is a hybrid that shuts off extra pistons when it is not accelerating