Runners only have enough stored ATP in their muscle cells to run for about five seconds. Which answer correctly explains how will the runner’s body adjust to the longer distance, for example, a marathon (42.1 km)?

The runner's body will convert stored fat molecules into energy.

The runner's body will create all of the needed energy through fermentation.

The runner's body will supply all of the needed energy through cellular respiration.


The runner's body will produce the ATP that is required through glycolysis.