14. Consider the following system of equations: $$\begin{cases} 5 x+7 y=8 \textbackslash\textbackslash{} 2 x+q y=r \end{cases}$$, where $q$ and $r$ are constants. If $q$ and $r$ are chosen such that this system has infinitely many solutions $(x, y)$, find $q+r=$~\uline{~~~~~~~~~~}~. 
选项为:A:$$6$$  B:$$8$$  C:$$9$$  D:$$12$$  请回答其中一个选项.