Transmitted power remaining the same, if supply voltage of a D.C. 2-wire feeder is increased 100 percent, saving in copper is____________________?

Transmitted power remaining the same, if supply voltage of a D.C. 2-wire feeder is increased 100 percent, saving in copper is____________________?

A. 25 percent
B. 50 percent
C. 75 percent
D. 100 percent