Final answer:
Charon is the biggest moon off of Pluto, with a diameter of about 1200 kilometers.
Step-by-step explanation:
According to the question. the biggest moon off of Pluto is Charon, with a diameter of about 1200 kilometers. Charon is approximately half the size of Pluto itself, making it the moon whose size is the largest fraction of its parent planet. From Pluto, Charon would appear as large as eight full moons on Earth.