Pat Can Either Drive to Work, Which Takes Half an Hour

Pat can either drive to work, which takes half an hour and uses $1.50 worth of gas, or take the bus, which takes an hour and costs $1.00. How should Pat get to work?

A) Pat should always take the bus because it costs $0.50 less.
B) Pat should always drive because it saves half an hour.
C) Pat should drive if saving a half hour is worth $0.50 or more.
D) Pat should take the bus if a half hour of time is worth $0.50 or more.