Idea you should reward your yourself for achieving study goals is based on

You can reward your's self with something you like (candy, a break or literraly anything else you like) so your'e motivated to keep working.

explanation: the line "to save the day, harry must get past a scary three-headed guard dog" from the summary best justifies the conclusion that harry potter and the sorcerer’s stone was influenced by ancient greek mythological literature. the three other choices had nothing to do with ancient greek literature - and the words "three-headed guard dog" are what makes that choice the correct answer.