Answer:
C: Security
Explanation:
Communications and information systems principles need to be, among other things, secure. They need to be able to protect sensitive information from those who intentionally not need to know. Some incident information like voice, networks, and data, are very sensitive and thus, should be secure to the right levels and should comply with privacy laws and data protection.
The answer is the first response, by order of elimination, you can eliminate the rest.
HTML is a programming language that is used to design websites. You don't need to program a website to make a post on instagram, especially if you are using the app.
If you check the app store on your phone, you can find instagram in the app store, which lets you access it from your mobile device. Thus, the third option is wrong.
Finally, just read the description of instagram. It was made for sharing pictures, so the last option is wrong.
A mail server. --------------------------------------------