SSL Forward Proxy acts as a Man-in-the-Middle, and certificate handling is critical for its success and potential issues. - Option A (Correct): Client-side certificates are presented by the client to the server for authentication. The firewall intercepting the connection cannot present the client's private key, breaking this type of authentication. - Option B (Correct): Certificate pinning means the client trusts only a specific certificate (hash or public key) from the server. The firewall presents a different certificate (signed by its CA), which the client rejects. - Option C: The Forward Untrust Certificate is used for sites with certificate errors or unknown status to explicitly warn users or block access, but the primary issue with trusted sites or internal apps is disruption caused by the MITM, not intentionally marking them untrusted. - Option D (Correct): If the firewall's Forward Trust Certificate is not installed and trusted on the client, the client will not trust any certificate signed by it, leading to certificate errors or warnings for sites that are decrypted. - Option E: Setting a rule to 'No Decrypt' would typically bypass decryption for those sites, preventing issues caused by the decryption process, not cause connection failures (unless combined with other policies).