Answer:
The author supports John Stein's claim that "Reading exercises the whole brain" (line 26) by explaining how functions of the brain are triggered
Step-by-step explanation:
After quoting John Steins's phrase the author explains how recent studies have shown that several sections of our brain get activated as we follow the story and start to imagine the events in there, these actions activates in our brain the same sections and processes that we would activate if we were actually doing the actions not only reading about them and that supports the theory of reading as an excellent way to exercise the brain.