AGit is the version control tool; GitHub is a hosting platform built on top of it
BGit is the hosting platform; GitHub is the command-line tool that talks to it
CThey are two names for the same distributed version control command-line tool
DGit is an older protocol that GitHub fully replaced with its own version system
Why this is the answer
Git is the tool (runs locally); GitHub hosts Git repos and adds PRs/Actions. The reversed option swaps their roles, they are not the same thing, and GitHub uses Git — it didn’t replace it.