If \( \left [ \begin{matrix} a & b \\ a_{1} & b_{1} \end{matrix} \right ] \left [ \begin{matrix} 3 & - 5 \\ - 1 & 2 \end{matrix} \right ] = \left [ \begin{matrix} 1 & - 1 \\ 2 & 0 \end{matrix} \right ] , \) then the values of a and b are ?

A a =1 and b=2

B a= 2 and b= 3

C a = 2 and b= 5