It's not a typo, answer B is correct.
Current T/L = Baggage + Mass of Pax
= 880 + 2772 + 2688 + 175
= 6515 kg
Current T/O Mass = DOM + T/L + Fuel
= 21600 + 6515 + 8500
= 36615 kg
Max Cargo Load = Max T/O Mass - Current T/O Mass
= 37200 - 36615
= 585 kg.
Hope this helps,