Which of the following protocols is used to secure communications between sender and receiver?

SIP (Session Initiation Protocol) is used for initiating, maintaining, and terminating real-time multimedia sessions, such as voice and video calls, but does not inherently provide communication security.

SNMP (Simple Network Management Protocol) is used for managing and monitoring network devices, not for securing general communication between applications or users.

SSL (Secure Sockets Layer), now largely superseded by TLS (Transport Layer Security), is a cryptographic protocol that provides secure communication over a computer network by encrypting data between a sender and receiver.

SMTP (Simple Mail Transfer Protocol) is used for sending and receiving email messages and does not inherently provide secure communication unless combined with other protocols like TLS.