For a surface with outward$-$pointing normal, n$,$ and a direction, $,$ toward the light source, which expression below is always true when the light source is below the surface?

n$\backslash$times $!=0$

n$\backslash$times $=0$

n$<0$

n$=0$

n$>0$

Note that $\backslash$times denotes the cross product and $$ denotes the dot product.