Fact 1: Riding a bike does not cause pollution.

Fact 2: Scientific consensus is that pollution causes global warming.

Given the two facts above, answer the question "Which of the following does not contribute to global warming?" with the following options: 
- nucleus of a cell
 - Flying in a plane
 - Leaving the lights on
 - haploid plants
 - a hydraulic system
 - Driving a car
 - Riding a bike
 - power stations


 

       Riding a bike  