{"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":"56c374690644e67ab7f8506fd73ed3641fc6fcf07a5c70a98e4540bc40e9a6f7"}