As compared to a 2-wire D.C. distributor, a 3-wire distributor with same maximum voltage to earth uses only__________________?

As compared to a 2-wire D.C. distributor, a 3-wire distributor with same maximum voltage to earth uses only__________________?

A. 31.25 percent of copper
B. 33.3 percent of copper
C. 66.7 percent of copper
D. 125 percent of copper