To get an output of 1 from the circuit shown in figure the input must be :

Question

$\begin{array}{1 1}(1) a=0, b=1, c=0 \\ (2) a=1, b=0, c=0 \\(3) a=1, b=0, c=1\\ (4) a=0, b=0, c=1 \end{array} $