Final answer:
Bluga should use Digital Signature, a form of asymmetric encryption that provides authentication and integrity to a message.
Step-by-step explanation:
Bluga should use d) Digital Signature. A digital signature is a form of asymmetric encryption that provides authentication and integrity to a message. It uses a private key to sign the message, which can be verified with a corresponding public key. This allows the recipients to know that the message definitely came from Bluga, as only Bluga possesses the private key. Additionally, the digital signature ensures that the message has not been tampered with during transmission.