The Capacitive Network Shown in the Figure Is Assembled with Initially

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