What come first a chicken or the egg?

Which phrase is the best summary of the model shown? a. the transfer of the sun's energy through trophic levels b. a series of aerobic and anaerobic reactions c. a transformation of light energy into chemical energy d. the breakdown of food molecules

Can someone me i need the answer and don’t understand?

Ascientist is examining the role of an element found in facts and carbohydrates of living things. this element makes up 65% of human body mass. which statement describes he is studying