A general expression of a vector field B is given by the expression B = 4xy  4yj + 4yzk and exists in the surface S shown below where a = 3.0 and d = 4.0 and the surface is parallel to the xz-plane. Assume n is the unit vector of the normal to the surface, pointed to the positive axis direction. v2 +k (a) What is the unit vector direction? (Choose from +i. -i, +j. -j, +k, -k) one point) (b) what is the final result of B. in symbolic form? m^2/C (2 points) (c) Calculate the numerical value of the flux S BndA through the surface given. Ignore any units, this is not an electric field.