Final answer:
The beginning of the Shang dynasty was marked by the overthrow of the last king of the Xia dynasty and is associated with the establishment of a Bronze Age civilization, around 1766 BCE.
Step-by-step explanation:
The event that marked the beginning of the Shang dynasty was neither the end of the Zhou dynasty, the end of the Iron Age, nor the death of Confucius. Instead, it was associated with the establishment of a complex, socially stratified Bronze Age civilization. The Shang dynasty began after the overthrow of the last king of the Xia dynasty. This transition is believed to have occurred around 1766 BCE, when the Shang civilization consolidated its power and began to flourish, known for the creation of written script through inscriptions on oracle bones, among other cultural advancements. Hence, the correct answer to the question is the start of the Bronze Age, which aligns with the rise of the Shang dynasty and its dominance over the region previously under control of the Xia dynasty.