Answer:
To help save the day, Harry must get past a scary three-headed guard dog.
Step-by-step explanation:
In Greek Mythology, Hades owns a three-headed guard dog, Cerberus, who serves him along with other multi-headed creatures. In this popular story of Harry Potter and his friends, the introduction of the guard dog suggests the utilization of allusion in the write-up.
However, the lines that determine this connection between Harry's story and the old Underworld's myths is written below :
"To help save the day, Harry must get past a scary three-headed guard dog."