主语是公园的门票,注意,公园只是用来限定门票这个主语,门票是复数,所以用are
B 在介词后面只能用whether,不能用if.例如：
①This depends upon whether we are determined to do it. 这件事要看我们是否有决心去做.
②It depends on whether he is ready. 这件事要看他是否有准备.
③I am not interested in whether you'll come or not. 你来不来我不感兴趣.
④We haven't settled the question of whether we'll renew our supplies of coal for factory. 是否要为我们工厂补充一些煤,这个问题我们还没有决定.