Comprehension \( \quad \) Let \( C \) be a curve \( f(x, y)=0 \) passing through \( (1,1) \) suc...

Comprehension \( \quad \) Let \( C \) be a curve \( f(x, y)=0 \) passing through \( (1,1) \) such that it is orthogonal to family of circles \( x^{2}+y^{2}-a x=0 \), where \( a \) being parameter.
If the curve \( C \) intersects the circle \( x^{2}+y^{2}+2 x+4 y+k=0 \) orthogonally then \( k \) is equal to
(a) 4
(b) 2
(c) 0