Which of the following protocols is responsible for sending and receiving emails across the internet? 

The Simple Mail Transfer Protocol (SMTP) is the standard protocol used for sending and receiving email messages over the internet. SMTP operates over TCP, typically using port 25 for transmission. When a user sends an email, the email client connects to the SMTP server, which then processes and forwards the email to the recipient's mail server. SMTP is essential for email delivery and is widely used in conjunction with other protocols, such as IMAP or POP3, which are used for retrieving emails from a server. Why Other Options are Incorrect: A) FTP (File Transfer Protocol): FTP is used for transferring files between hosts but is not used for email transmission. B) HTTP (Hypertext Transfer Protocol): HTTP is the protocol for transferring web pages and resources but does not handle email. D) SNMP (Simple Network Management Protocol): SNMP is used for managing and monitoring network devices, not for sending or receiving email. E) ICMP (Internet Control Message Protocol): ICMP is used for sending error messages and operational information regarding network connectivity but does not relate to email transmission.