Edgar Allan Poe is often called as the originator of the short story as an established genre. He defined ‘the prose tale’ as:

The correct option is: A narrative which can be read at one sitting of from half an hour to two hours.

Explanation:
Edgar Allan Poe, a pivotal figure in 19th-century American literature, is widely credited with establishing the critical guidelines for the modern short story, which he referred to as the "prose tale." In his famous 1842 review of Nathaniel Hawthorne's Twice-Told Tales, Poe articulated his literary theories regarding brief narrative fiction.

Poe argued that the most crucial element of a successful prose tale is the "unity of effect" or "single effect." According to his theory, a writer should first conceive of a single, unique effect they wish to produce in the reader's mind, and then fashion all incidents, characters, and words to serve that pre-established design.

To achieve this undivided emotional and intellectual impact, Poe insisted that the narrative must be read in one continuous session. If a story is too long to be read at once, the interruptions of daily life break the spell and destroy the unity of effect. Therefore, he defined the ideal prose tale as a narrative requiring from half an hour to two hours in its perusal, allowing the reader to consume it in a single sitting without distraction.