If \mathrm{A}(4,2), \mathrm{B}(6,5) and \mathrm{C}(1,4) be the vertices of \triangle \mathrm{ABC} and \mathrm{AD} is a median, then the coordinates of \mathrm{D} are (a) \left(\frac{5}{2}, 3\right) (b) \left(5, \frac{7}{2}\right) (c) \left(\frac{7}{2}, \frac{9}{2}\right) (d) none of these