A country club usually only allows members to attend the 4th of July party, but the country club is considering allowing non-members to attend. The demand and supply schedules are as follows: Price Quantity Demanded by members Quantity Demanded by Non-members Quantity Supplied
$10 1000 500 600
$15 800 400 600
$20 600 300 600
$25 400 200 600
$30 200 100 600

If both members and non-members are allowed to purchase tickets to this year's celebrity golf tournament and the country club sets the ticket price at $20, then there will be:

a. a shortage of 300 tickets.
b. a surplus of 300 tickets.
c. 600 tickets sold.
d. 600 tickets unsold.