Fact 1: Humans have collected and grown mushrooms for food for thousands of years.

Fact 2: Foods rich in chlorine are mushrooms, parsley, sweet potato, rhubarb, and especially tomato.

Given the two facts above, answer the question "Humans have collected and grown foods rich in what for thousands of years?" with the following options: 
- glucose
 - bacteria
 - ferns
 - chlorine
 - acetic acid
 - Energy.
 - heat energy
 - Energy


 

    chlorine     