Answer: Smart Card.
Explanation: A Personal Identity Verification device is a smart card that is used to store a user's digital identity and provide secure access to government computer systems. By requiring users to use a PIV device when sending digitally signed and encrypted emails, the government contractor is implementing the use of smart cards as a physical security measure. Smart cards are secure, portable, and can be used to provide strong authentication and encryption for a wide range of applications, including digital signatures and encrypted emails. They offer a high level of security by requiring a user to physically possess the card in order to access its stored information.