Sarah Initially Used Her Cell Phone Mostly to Make Important

Multiple Choice

Sarah initially used her cell phone mostly to make important business calls.However,when she was informed that henceforth her phone bills would be reimbursed by her employer,she started using her cell phone to make frequent calls to her friends and relatives.This behavior is an example of ________.

A) moral hazard
B) a negative externality
C) the prisoners' dilemma
D) the free-rider problem