"which line from the summary best justifies the conclusion that harry potter and the sorcerer’s stone was influenced by ancient greek mythological literature? "

The conclusion that Harry Potter and the Sorcerer’s Stone was influenced by Ancient Greek mythological literature:

In harry potter one of the most remembered scene is when harry and his friends try get into a chamber where a three headed dog live, which was Hagrid’s pet that time, It relates to the Greek myth creatures as Greek myth creatures are powerful and  deadly, which resembled the dog with 3 heads in the Greek mythology literature. It was known as the Cerbius, Guardian of one of the important and plot twisting chambers in the Harry Potter franchise.

Also Jk Rowling was a huge of Greek Myth, she always inculcated all of these things in her writings.  This is how Greek myth relationship and influence between harry potter started.