Which internet protocol is used to transmit encrypted data?

Answer: HTTPS

Explanation: 

HTTPS is an extension to the HTTP protocol that enables secure, encrypted communication over a network. HTTPS works by using SSL/TLS technology to create a secure connection between your web browser and the website you're visiting. This means that all of your data - including your passwords and bank details - is safe from prying eyes. HTTPS is becoming more and more common, as websites start to realise the benefits of using it. Not only is it more secure, but it also makes browsing more user-friendly - meaning you don't have to worry about any unwanted ads or tracking cookies.