B was based on BCPL, which I assume is where the name came from.
But the actual A language would be APL, which stands for A Programming Language. It’s a few years older than B and was pretty popular, so it could’ve influenced the name.
A Programming Language
Gotta admire the wherewithal of continuing down the alphabet rather than just “Another Programming Language”, through “Yet Another Programming Language” to “Dude, Where’s My Programming Language”.