The default port number for HTTPS is 443.
Port numbers are used to identify the specific service that is being accessed on a computer. For example, port 80 is used for HTTP, the protocol that is used to transfer web pages. Port 443 is used for HTTPS, the secure version of HTTP.
When you type a URL into your web browser, the browser sends a request to the server at that address. The server then responds with the requested page, which is sent back to the browser over the same port that the request was made on.
If you are using HTTPS, the request and response will be encrypted, which means that they cannot be read by anyone who is intercepting the traffic. This is important for security, as it prevents people from being able to see what you are doing on the internet.
The other options are incorrect because they are not the default port numbers for HTTPS. Port 80 is the default port number for HTTP, port 40 is not a valid port number, and port 20 is the default port number for FTP.