Final answer:
Pharaoh Akhenaten (Option B) is responsible for the marked break in the traditional canon of Egyptian art during the Amarna Period by promoting monotheism and altering artistic styles.
Step-by-step explanation:
The marked break with the traditional canon of Egyptian art occurred during the rule of pharaoh Akhenaten, originally known as Amenhotep IV. Akhenaten radically changed Egyptian religion and art by introducing monotheism centered on Aten, the sun god, and shifting the artistic style to a more realistic portrayal. This period of change is known as the Amarna Period, which featured works of art that deviated significantly from the norm, including representations of Akhenaten in a more androgynous form. These notable changes were short-lived, however, ending with Akhenaten's death in 1336 BCE when Egypt returned to its traditional gods and styles.