The locus represented by $xy+yz=0$ is

Question

$$\begin{array}{1 1}(A)\;A\; pair\; of\; perpendicular\; lines & (B)\;A\; pair\; of\; parallel\; lines\\(C)\;A\; pair\; of\; perpendicular\; planes & (D)\;A\; pair\; of\; parallel\; lines\end{array}$$