Fact 1: Veins generally carry deoxygenated blood.

Fact 2: Deoxygenated blood is heavy with carbon dioxide.

Given the two facts above, answer the question "What is blood heavy with?" with the following options: 
- Carbon monoxide
 - Energy.
 - Bacteria
 - Chemical energy
 - matter vibrating
 - Carbon dioxide
 - Veins and arteries.
 - Water


 

      Carbon dioxide   