Carpooling decreases the amount of cars used to travel to a place, and carpools and vanpools can save time. Given these facts, what decreases the amount of cars used to travel to a place among the following options:
- single-driver cars
 - motorcycles
 - Riding a bike
 - gas guzzlers
 - energy barrier
 - Temperature
 - vanpooling
 - adding heat


 

       vanpooling  