Which of the following is an example of a biological system?
O
A. The heart, lungs, and blood vessels working together to carry
oxygen throughout the body
O
B. A science fair project modeling the process of breathing in the
human body
O
C. A biology textbook
D. The Internet

the answer would be   10%

answer; endometriosis;

explanation:

the sun shines white and black light to our planet. the white light has all the colors in it. in our upper atmosphere, we have dust particles and oxygen molecules. the white light meaning all of the colors in a rainbow shines through the upper levels of the atmopshere and the blue light scatters across the entire planet. that is why our sky is blue.