Capacitors in Combination: the Capacitive Network Shown in the Figure

Capacitors in combination: The capacitive network shown in the figure is assembled with initially uncharged capacitors. A potential difference, V_ab = +100V, is applied across the network. The switch S in the network is kept open. Assume that all the capacitances shown are accurate to two significant figures. What is potential difference V_cd across the open switch S?

A) 0 V
B) 40 V
C) 50 V
D) 60 V
E) 70 V