16. When your body needs additional energy, like when you run, things happen in your body systems to give you the additional food and oxygen you need in your cells. Which of the following is happening to send more energy to cells when you are running? 1. Your skeletal system gets stronger. II. Your digestive system breaks down food faster. III. Your heart pumps blood with more force. IV. Your lungs work harder and faster.​

i believe the correct answer from the choices listed above is the first option. the scientists need to look at the   validity of data, claims, hypotheses, and observations before  developing an argument. they base their arguments on facts that are present and they make sure they have proofs. 

explanation:

frogs. the lower the ph the higher the acid content. frogs have the highest tolerance in this scenario.

answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]