A tank filled with $200$ litres of water weighs $350\rm{kg}$. The same tank filled with $150$ litres of water weighs $315\rm{kg}$. What is the weight of the empty tank? 
选项为:A:$$120\rm{kg}$$  B:$$150\rm{kg}$$  C:$$165\rm{kg}$$  D:$$210\rm{kg}$$  E:None of the above  请回答其中一个选项.