$a,b,c$ are natural no and equations $x^2-5x+a=0,x^2-6x+b=0,x^2-8x+c=0$ have exactly one root in common and common root is also a natural no.(a+b+c) is maximum when common root is :

Question

$\begin{array}{1 1}(A)\;1&(B)\;3\\(C)\;4&(D)\;\text{None}\end{array} $