For choice A, we can rearrange the equation to so it has exactly one solution,
For choice B, we rearrange the equation to so this too has exactly one solution,
Rearranging the equation in choice C by eliminating the terms gives us the false equality
so this equation has no solutions.
Eliminating in the equation in choice D gives the equality
which is always true, so this equation has infinitely many solutions.
Thus, we conclude that choices A and B work.