We can determine the correct graph by finding its roots
x² - 4x - 12 = 0
x² - 6x + 2x - 12 = 0
x(x-6) +2(x-6) = 0
(x+2)(x-6) = 0
This means the roots of the function are x=-2, and x=6 and the graph will cross x axis at these two points. From the given graphs, the graph B seems to cross these points.
