The sequence increases in this order: $$300$$, $$400$$, $$500$$, $$600$$, $$\dots$$ 
$$1423$$, $$1723$$, $$2123$$,~\uline{~~~~~~~~~~}~, $$3223$$  Which one of the following is the missing number? 
(a) $$2523$$ 
(b) $$2623$$ 
(c) $$2723$$ 
(d) $$2823$$ 