A liquid is filled into a tube with semi-elliptical cross-section as shown in the figure. The ratio of the surface tension forces on the curved part and the plane part of the tube in vertical position will be
(a) $\frac{\pi(a+b)}{4 b}$
(b) $\frac{2 \pi a}{b}$
(c) $\frac{\pi a}{4 b}$
(d) $\frac{\pi(a-b)}{4 b}$