In 2004, a large department store chain in Germany was forced to withdraw customer loyalty cards when the press discovered that the company had secreted radio-frequency identification (RFID) tags in the plastic. Even when enclosed in a wallet or purse, these cards can transmit information over distances of about a meter, and the stores planned to use them to track which departments the customer visited. At issue was which data security issue? a. information keystoningb. data miningc. data warehousingd. data outsourcinge. patterning