Identify the topic sentence in the given paragraph. All members of the animal kingdom need sleep to help their brains function properly. The brain needs a minimum number of hours to rest and organize itself. The number of hours depends on age. For example, human babies need an average of 14 to 16 hours of rest daily, while adults can function on about 6 to 8 hours. Scientists are not completely sure what the brain does during sleep periods, but they do know that the brain sorts and stores information and replaces chemicals when a person sleeps.

Read this passage: byron and mitch are co-captains of the mathletes, their high school's academic team. they are backstage with the five other team members, preparing to compete in the state math quiz. byron sits on the floor with his eyes closed and his earbuds in, listening to classical jazz, which him focus his mind and energy. suddenly, he feels a presence beside him. he opens his eyes to see mitch staring at him. "mathletes! mathletes! " mitch chants loudly. mitch gives byron a thumbs-up and then proceeds to strut around like a peacock, high-fiving the other team members, as byron shuts his eyes again and does his best to refocus his mind which statement best summarizes the passage?