Find the equation of tangent at the point $p(x_1,y_1)$ to a circle $x^2+y^2+2gx+2fy+c=0$?

Question

$\begin{array}{1 1}(a)\;xx_1+yy_1+g(x+x_1)+f(y+y_1)+c=0\\(b)\;xx_1+yy_1+g(x+x_1)-f(y+y_1)+c=0\\(c)\;xx_1+yy_1-g(x+x_1)-f(y+y_1)-c=0\\(d)\;xx_1-yy_1-g(x+x_1)-f(y+y_1)-c=0\end{array}$