Which of the Following Most Embodies the Principle of Data

Which of the following most embodies the principle of Data Protection by Default?

A) A messaging app for high school students that uses HTTPS to communicate with the server.
B) An electronic teddy bear with built-in voice recognition that only responds to its owner's voice.
C) An internet forum for victims of domestic violence that allows anonymous posts without registration.
D) A website that has an opt-in form for marketing emails when registering to download a whitepaper.