Fact 1: Carpooling decreases the amount of cars used to travel to a place.

Fact 2: Carpools and vanpools can save time.

Given the two facts above, answer the question "What decreases the amount of cars used to travel to a place?" with the following options: 
- single-driver cars
 - motorcycles
 - Riding a bike
 - gas guzzlers
 - energy barrier
 - Temperature
 - vanpooling
 - adding heat


 

       vanpooling  