The first person to answer all will be marked brainliest!

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

Veins have a much lower blood pressure than arteries. which of these prevents backflow of blood in veins? a. pressure applied by the heart b. one–way valves in veins c. thin muscular walls of veins

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