The correct options are
A kingdom and the dynasties that ruled it
B society of medieval Kerala
C language and script used by the people
D period of king's reign
Copper plates were useful archaeological sources as it tells us about a variety of things. It tells us about the kingdom and the dynasties that ruled the kingdom. It also tells us about the society of medieval Kerala. It talks about traders, kings and farmers. It also talks about the language and the script used by the people of Medieval Kerala. It is also helpful in recording the period of king's reign.