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