15.) let c denotes the boundary of the semi-circular disk d {(x, y) e r2:x2 + y2 s1y2 0) and let (x, y) = x*+ y for (x, y) e d. if h is the outward unit nomal

15.) Let C denotes the boundary of the semi-circular disk D {(x, y) e R2:x2 + y2 s1y2 0) and let (x, y) = x*+ y for (x, y) e D. If h is the outward unit nomal to C, then the integral (Vo).n ds, evaluated counter-clockwise over C, is equal to (a) 0 (b) n -2 (c) Tt (d) t +2