Final answer:
Copper and bronze coins in China appeared around 500 BCE, during a period when bronze technology was highly advanced and integral to Chinese civilization, particularly within the Shang dynasty.
Step-by-step explanation:
The appearance of copper and bronze coins in China can be traced back to the advancement of metallurgy and the widespread use of bronze in Chinese civilization. Bronze, an alloy mainly composed of copper and small amounts of tin or lead, was a fundamental aspect of the Shang dynasty, dating back to approximately 1500 BCE. This period is marked by significant technological innovations, making the Early Shang dynasty a formidable power with their use of bronze in creating weapons, ritual vessels, and other artifacts. From the available choices, it is evident that copper and bronze coins appear in China around option 'a. 500 BCE'. This assertion aligns with the historical context which indicates that, by the Bronze Age, Chinese metallurgy was sufficiently advanced to produce ceremonial and practical objects, and the technology was present during the Shang dynasty, well before 500 BCE.