Final answer:
The sentence that best fits as a specific supporting detail is Option A: "This marked the beginning of Egypt's long history of pyramid construction."
Step-by-step explanation:
The passage under consideration discusses the political history and cultural developments in ancient Egypt, particularly focusing on the structure and achievements of its dynasties.
When considering a specific supporting detail that could be added to the passage, the correct choice is one that aligns with the historical facts presented about the era being described. From the provided details, we learn about the unification of Egypt and the subsequent culture and construction practices that followed.
The most fitting additional detail that aligns with the Early Dynastic Period and the feats of the subsequent dynasties is the advent of pyramid construction as a form of monumental architecture. This is well-supported by the information about Djoser and his architect Imhotep, who built the step pyramid as a sophisticated stone tomb for the pharaoh, which predates the Old Kingdom and the illustrious pyramids that continue to captivate visitors today.
Therefore, the sentence that could be added to the passage as a specific supporting detail is: "This marked the beginning of Egypt's long history of pyramid construction." Option A not only aligns with the architectural achievements of the time but also with the reign of Djoser who was known to commission the first pyramid.
Option B mentioning the Great Wall of Egypt, Option C discussing a written legal code, and Option D referring to the emergence of a democratic government are not supported by the historical context provided and are not accurate according to historical records of that period.