Final answer:
A digital signature refers to a cryptographic code that is used to verify the authenticity and integrity of a digital document or message. It involves a technique called public key encryption. Hence the correct answer is option C
Step-by-step explanation:
A digital signature refers to a cryptographic code that is used to verify the authenticity and integrity of a digital document or message.
It is not a scanned signature on a computer or a code number of the sender. Rather, it involves a technique called public key encryption, where the sender uses their private key to create a unique digital signature that can only be verified by the recipient using the sender's public key.
So, the correct answer to this question is C. Public Key Encryption.