Sleep deprivation harms memory. Overtired teens are more prone to accidents. Teens dealing from sleep deprivation lose the ability to focus.
These three options would be support Joao's rebuttal because they show how harmful sleep deprivation can be. Joao needs to show that starting classes later will allow students to get more sleep and therefore not succumb to the harmful effects of sleep deprivation. The other options do not support his rebuttal because they are not relevant to students AND sleep. In fact, saying that researchers do not know why human beings need to sleep goes against his rebuttal because it sounds like humans don't need as much sleep.