The bottom symbol in B is a fairly common symbol for a motor.
The other one seems to be an uncommon symbol for a generator. This page identifies it as a DC generator:
But this page says it's "AC power":
Both pages are missing the + and - signs. The presence of + and - signs and the overall context suggest it's meant as a DC generator, or (less likely) a generic voltage source.
Unfortunately, as my links show, there's not a lot of consistency in these kinds of symbols.