A hollow conductor is positively charged. Asmall uncharged metal ball is lowered by a silk thread through asmall opening in the top of the conductor and allowed to touch itsinner surface. After the ball is removed, it will have.

a. a positive charge
b. a negative charge
c. no appreciable charge
d. a charge whose sign depends on what part of the innersurface it touched
e. a charge whose sign depends on where the small hole islocated in the conductor