只有A是正确的.
Not only are they not shunned, but seats are proffered, doors smilingly held open for pram-pushing mothers and tables miraculously appear in crowded restaurants.
Not only前置句型,同时后面的主谓/主表倒装,表示强调.
这句话的意思是：人们不仅没有回避/躲开那些推着婴儿车的母亲们,还给他们让座、扶着门开着,还给他们让出餐桌.
though与despite与but不搭；B与句型、句意不合.