Final answer:
Professor McGonagall was looking through the curtains to see the dragon in Hagrid's hut.
Step-by-step explanation:
The statement accurately identifies that Professor McGonagall was the one looking through the curtains to observe the dragon in Hagrid's hut.
This event takes place in the first book of the Harry Potter series, "Harry Potter and the Philosopher's Stone" (also known as "Harry Potter and the Sorcerer's Stone" in the United States).
In this scene, Hagrid wins a dragon egg in a card game at the Hog's Head Inn and decides to hatch it. Professor McGonagall, along with Professor Dumledore and Professor Snape, goes to Hagrid's hut to investigate the situation.
It is during this visit that Professor McGonagall peeks through the curtains to witness the dragon. This incident is part of the unfolding plot as the characters navigate the challenges posed by the presence of the dragon at Hogwarts.