Final answer:
The traditional port for SMTP is 25, but port 587 is also commonly used for secure email submission. Port 25 is mainly used for communication between mail servers.
Step-by-step explanation:
The port for SMTP, which stands for Simple Mail Transfer Protocol, is used primarily for sending emails. The correct answer to the student's question is that Option 1: Port 25 is the traditional port used for SMTP. However, due to modern security practices, Option 4: Port 587 is also commonly used for SMTP when submitting emails to a mail server for sending.
Port 465 was also used for SMTPS (SMTP over SSL), but it's not an official standard and is being phased out in favor of port 587 with STARTTLS. Port 389 is typically used for LDAP (Lightweight Directory Access Protocol), and Port 443 is for HTTPS (Hypertext Transfer Protocol Secure).