Which ONE of the following statements is TRUE? OA. The cross product of the gradient and the uint vector of the directional vector gives us the directional derivative. OB. None of the choices in this list. OC. The directional derivative as a scalar quantity is always in the direction vector u with u = 1. 0. Gradient of f(x...) at some point (a,b,c) is given by ai+bj+ck. OE. The directional derivative is a vector valued function in the direction of some point of the gradient of some given function.