Free electrons may be transferred between bodies by:
a) heat loss
b) contact action
c) at a distance

B) contact action

Explanation:

When two conductors are connected with each other then in that case the free charge of one conductor may be transferred to other if the potential of one conductor is not same as the potential of other conductor.

As we know that positive charge always move from higher potential to lower potential.

So here when two bodies are connected together then in that case electron from one body is transferred to other body if the the potential of two bodies are not same.

So here correct answer will be

B) contact action

carla slowed down in the beginning of her trip, stopped, and then sped up

v=ir = 3x15 =45 v