Which line from the summary best justifies the conclusion that Harry Potter and the Sorcerer’s Stone was influenced by Ancient Greek mythological literature?

To help save the day, Harry must get past a scary three-headed guard dog.
In order to do this, he gets help from his good friends Hermione and Ron.
They all have become close friends during the course of the school year.
After they solve this challenge, they move on to the next part of their plan.