This passage refers to researchers. What do these researchers study?

What is the relationship between paragraph 2 paragraph 3 through 29?

Diego rivera was a famous artist from mexico. most of his paintings were murals. murals are paintings that are made directly on a wall. rivera thought that all people should be able to see beautiful art, not just people who could afford to go to museums. this is why he painted most of his murals on the walls of public buildings

The function described as consumption and the absorption of energy through photosynthesis is called a. respiration b.energy absorption/food consumption c.excretion d. re-charge