Answer:
Gene, a part of DNA that determines the trait of individual characteristics
Explanation:
This process helps the necessary areas in the body to get the nutrients the blood carries. this is the curculatory system included with the other systems that creates a type of substance or nutrient the body needs.
If all humans had the same DNA, and one person got the cold, everyone would die at some point. The more diversity there is the more chance of surviving an outbreak or natural disaster or something. Think of the flu. there are HUNDREDS of strains out there. some are resistant to our medicines and others aren't.
Most likely A from my point of view
