A certificate authority (CA) is critical in a public key cryptographic system for mitigating man-in-the-middle (MITM) attacks. It ensures that public keys are authentic by issuing digital certificates, which bind a public key to an entity. The CA’s role in verifying identities and providing trust anchors prevents attackers from spoofing keys.

Strong Encryption Algorithms (Option A):Encryption ensures confidentiality but does not address spoofing risks.

Kerberos Authentication (Option B):Useful for mutual authentication but not central to public key infrastructure (PKI).

Registration Authority (Option C):Supports the CA but does not directly prevent MITM attacks.