What is a big concern for general admission seating (first come–first served) because seats are not reserved?

a. This type of ticket holder always arrives late.
b. This type of ticket is easy to counterfeit.
c. The resale value of these tickets always goes down.
d. Ticket holders might scuffle in the venue over the best seats.

d. Ticket holders might scuffle in the venue over the best seats.