A computer can do $$7\times {{10}^{9}}$$ operations per second. Then, it can do~\uline{~~~~~~~~~~}~operations in $$5\times {{10}^{2}}$$ seconds. 
选项为:A:$$35\times {{10}^{10}}$$  B:$$3.5\times {{10}^{11}}$$  C:$$3.5\times {{10}^{12}}$$  D:$$3.5\times {{10}^{19}}$$  E:$$3.5\times {{10}^{18}}$$  请回答其中一个选项.