Since there are five solutions to the equation about x, let's first give it according to the universal formula.

That is, two straight lines parallel to the x axis.

Let f(x 1)>f(x2)

There are five solutions that can be understood as the five intersections of the lower f(x) (two straight lines) and the above diagram (you can understand why you understand this). If you can understand clearly here, the following part will be easy to handle.

Then two straight lines parallel to the X axis must have five intersections with the image. There are obviously only two situations, as shown in the figure.

In this case, f (x 1) >: 6, f(x2)=6, a <-12.

In this case, there are exactly five intersections. When f(x 1)=6 and f(x2)=-3, a=-3 is calculated.

So the answer is B.