{"p":"can-20","op":"mint","tick":"can","amt":"1000","rows":[{"df":"qa","content":[{"q":"The security guarantee mechanism in blockchain refers to what?","a":"Transaction immutability: Once a  transaction is recorded in the blockchain, it cannot be altered or deleted. This feature ensures"}]}],"pr":"221de22171402f8e94bf5268f91c6aad931240064e29175abdf1800ac7907d08"}