The condition for the equation $x^2+(\lambda +\mu )xy+\lambda \mu y^2+x+\mu y=0$ to represent pair of parallel lines and the distance between them are

• A

  $\lambda +\mu =0,\sqrt{1+{\mu }^2}$

• B

  $\lambda +\mu =0,\frac{1}{\sqrt{1+{\mu }^2}}$

• C

  $\lambda =\mu ,\sqrt{1+{\mu }^2}$

• D

  $\lambda =\mu ,\frac{1}{\sqrt{1+{\mu }^2}}$