Who defined ‘hamartia’ as ‘tragic flaw’?

The correct option is Aristotle.

Explanation:
The concept of hamartia originates from ancient Greek literature and drama, and was formally defined and analyzed by the Greek philosopher Aristotle in his seminal work, the Poetics (circa 335 BCE).
In his analysis of tragedy, Aristotle used the term hamartia (derived from the Greek word meaning "to err" or "to miss the mark") to describe the inherent error of judgment, miscalculation, or defect of character in a tragic protagonist. This error ultimately leads to their downfall or reversal of fortune (peripeteia). In literary criticism, this concept is commonly translated and understood as the protagonist's "tragic flaw," making Aristotle the source of this definition.