Fact 1: An animal requires air for survival.

Fact 2: It is breathed in by animals and restored to the air by the photosynthesis mechanism of plants.

Given the two facts above, answer the question "Animals rely on what for survival?" with the following options: 
- proteins
 - glycogen
 - rocks
 - sunlight
 - stars
 - weeds
 - cellulose
 - plants


 

        plants 