The line integral of a scalar function f(x,y) along a contour ,s, with t as a parameter, is (a) So f (x, y) ds (b) So f (x (t) , y (t) ) Ir' (t) ldt (c) SF . Tds (d) So F . r' (t) dt (e) So F . dr O a Ob O c O d O e