A Vector a Has a Magnitude |A| and Makes an Angle

Multiple Choice

A vector A has a magnitude |A| and makes an angle $\theta$ with respect to the y axis in a two-dimensional rectangular coordinate system. A_x is

A) |A| sin $\theta$ .
B) |A| cos $\theta$ .
C) |A| tan $\theta$ .
D) none of the above.