Final answer:
A person who can play the piano exceptionally well without having taken lessons and is deaf would be described as a savant.
Step-by-step explanation:
The term used to describe a person who plays the piano without ever having taken a lesson and is deaf is c) Savant. A savant is someone who demonstrates profound and prodigious capacities or abilities far in excess of what would be considered normal, often including the ability to perform music with great skill despite having significant disabilities, such as deafness, and without formal training. The terms virtuoso and maestro are usually used for highly skilled and trained musicians, while prodigy refers to a young person with exceptional talents or abilities.