The second and fourth choices. This is because both of those are easily factored (or already factored!) and those factors can be set equal to zero to solve for x.
The fourth one is already factored, and the second one can be factored into
[tex]4x(x + 4) = 0[/tex]
which can be solved for x easily.
The other two equation are either too complicated to factor fast or do not factor.
