Let P be a point on the parabola y2=4ax, where a>0. The normal to the parabola at P meets the x-axis at a point Q. The area of the triangle PFQ, where F is the focus of the parabola, is 120. If the slope m of the normal and a are both positive integers, then the pair (a,m) is
(A) (2,3)
(B) (1,3)
(C) (2,4)
(D) (3,4)