A marathoner's leg muscles often feel heavy and prone to cramping after 20 or more miles. Which of the following is the best explanation for this?
O A marathoner's circulatory and respiratory system cannot take in sufficient oxygen, and the
muscle cells must switch to anaerobic respiration for energy.
O A marathoner's muscle cells contract when glucose reacts with oxygen.
O A marathoner's circulatory system takes in too much oxygen during a race, which causes
muscle cramping.
O A marathoner's muscle cells cannot store glucose for use as energy.

Clara wrote the following hypothesis for an experiment about acidophilic bacteria. bacteria cells will stop dividing in a basic (alkaline) environment because of the high ph. which statement is the best way to restate the hypothesis so that it is more specific? growing acidophilic bacteria in some environments will cause the cells to stop dividing because of ph. if the ph of their environment is changed, acidophilic bacterial cell division will be affected. if the environment of acidophilic bacterial cells becomes alkaline, the bacteria will stop dividing. the more alkaline an environment, the less cell division will occur in bacteria.