Please help me with this

Time left 2:25:54 Supply $15 $12 Social value Demand 500 700 Quantity of boxes of softella medicated tissues The figure above shows a market for Softella medicated tissues. Assume the only use for the tissues is to wipe and clean your hands, which prevents the spread of germs to others. If the government were to subsidize the users of the tissues, what would be the dollar amount of the subsidy? Select one: O a. $15 O b. $4 O c. O d. $7