Final answer:
Public Key Infrastructure (PKI) is the system to encrypt and decrypt digital signatures and protect passwords from disclosure. It employs digital certificates to ensure secure transactions. Users should also maintain strong passwords and secure their personal information with antivirus software and vigilant personal security practices.
Step-by-step explanation:
The correct answer is A) Public Key Infrastructure (PKI). PKI is a set of roles, policies, hardware, software, and procedures needed to create, manage, distribute, use, store, and revoke digital certificates and manage public-key encryption.
It is essential for various security tasks, such as encrypting and decrypting digital signatures, which ensures that a document or transaction is authentic, and protecting passwords from disclosure by encrypting them. A digital signature not only helps in authenticating the identity of the sender of a message or signer of a document, but also provides non-repudiation, meaning it can prevent the claim that a signer did not sign a document.
To protect your credit and debit cards and personal information, it's vital to use strong passwords and PINs that cannot be easily guessed, and take other security measures like using anti-virus software on your computer, protecting your mailbox from theft, and notifying your bank whenever you change your address or phone number.