# If $x-y+1=0$ meets the circle $x^2+y^2+y-1=0$ at A and B , then the equation of the circle with AB as diameter is :

$\begin {array} {1 1} (a)\;2(x^2+y^2)+3x-y+1=0 & \quad (b)\;2(x^2+y^2)+3x-y+2=0 \\ (c)\;2(x^2+y^2)+3x-y+3=0 & \quad (d)\;x^2+y^2+3x-y+1=0 \end {array}$

$(a)\;2(x^2+y^2)+3x-y+1=0$