The parabola with directrix $x+2y-1=0$ and focus (1,0) is :

$\begin {array} {1 1} (a)\;4x^2-4xy+y^2-8x+4y+4=0 & \quad (b)\;4x^2+4xy+y^2-8x+4y+4=0 \\ (c)\;4x^2+5xy+y^2+8x-4y+4=0 & \quad (d)\;4x^2-4xy+y^2-8x-4y+4=0 \end {array}$

$(a)\;4x^2-4xy+y^2-8x+4y+4=0$