What component of earth’s atmosphere exists entirely as a result of photosynthesis? a)oxygen gas b)water vapor c)nitrogen gas d)carbon dioxide gas

I’m doing some practice exam questions for biology, and i’m not sure how to do these 3 parts to the question.

Body systems are not completely independent they integrate and work together describe one example of the integration between body systems

Plz ! cattle ranchers and dairy farmers rarely allow all of their animals to reproduce instead they practice selective breeding and only encourage the reproduction of animals with specific features. which of the following cows would a dairy farm most likely choose to reproduce? a. a cow that makes a lot of milk. b. a cow that can run quickly. c. a cow with a think, soft fur. d. a cow with large, strong hooves.