Final answer:
Alex is most likely a savant, as he possesses an extraordinary ability to reproduce complex musical pieces despite his intellectual disability. Savant syndrome differs from dyslexia and autism, as it involves remarkable skills beyond the norm. A prodigy is a young talented individual without developmental disabilities.
Step-by-step explanation:
25-year-old Alex who has an intellectual disability and cannot read or write, yet can precisely reproduce complex musical pieces on the piano after a single listening, is most likely exhibiting savant syndrome. Savant syndrome is a condition in which a person with a developmental disability demonstrates profound and prodigious capacities or abilities far in excess of what would be considered normal. This condition is distinct from dyslexia, which is a common learning disability characterized by difficulties in processing language, specifically problems related to reading, writing, and spelling. While autism spectrum disorder (ASD) can sometimes involve traits that overlap with savant syndrome, such as intense focus and memory for specific areas of interest, not all individuals with autism are savants. In contrast, a prodigy generally refers to a young person with extraordinary talent or ability in a particular area but does not necessarily have a developmental disability. Given the information provided, it is likely that Alex exhibits characteristics of a savant.