In the window of Bradley\textquotesingle s Bicycle Bazaar there are some unicycles, some bicycles and some tricycles. Laura sees that there are seven saddles in total, thirteen wheels in total and more bicycles than tricycles.  How many unicycles are in the window? 
选项为:A:$$1$$  B:$$2$$  C:$$3$$  D:$$4$$  E:$$5$$  请回答其中一个选项.