When is it possible to use a self-signed certificate, rather than one purchased from a commercial certificate authority?

When is it possible to use a self-signed certificate, rather than one purchased from a commercial certificate authority?
A . If you are a small business or home office
B . If you are an enterprise whose employees use only mobile devices
C . If you are an enterprise whose resources do not need security
D . If you are an enterprise whose computers all trust your active directory or other CA server

Answer: C

Explanation:

This can include SSL/TLS certificates, code signing certificates, and S/MIME certificates. The reason why they’re considered different from traditional certificate-authority signed certificates is that they’re created, issued, and signed by the company or developer who is responsible for the website or software being signed. This is why self-signed certificates are considered unsafe for public-facing websites and applications.

Reference: https://sectigostore.com/page/what-is-a-self-signed-certificate/