Here is the item again:
O'Neil quietly closed the front door and tiptoed through the living
room. Hoping not to wake his sleeping mother, who would begin a loud and
long lecture on missing curfew.
You chose to use Punctuation Rule 3 to fix the problem:
Main Clause + , + Participle Phrase.
Here is the correction:
O'Neil quietly closed the front door and tiptoed through the living
room,
hoping not to wake his sleeping mother, who would begin a loud and
long lecture on missing curfew.
Well done! You deserve that chocolate bar!