The correct option is (a) 3 double bonds and a single bond
The explanation: The formula for perchloric acid is HOClO3, in which the chlorine group is attached to 3 oxygen atoms and a hydroxyl group. The 3 oxygen atoms are attached to chlorine through a double bond and the hydroxyl group is singly bonded to chlorine. Thus, there are 3 double bonds and a single bond between oxygen and chlorine.