The line graph L(G) of a simple graph G is defined as follows:
There is exactly one vertex v(e) in L(G) for each edge e in G.
For any two edges e and in G, L(G) has an edge between v(e) and v(), if
and only if e and e- are incident with the same vertex in G.
Which of the following statements is/are TRUE?
(P) The line graph of a cycle is a cycle.
(Q) The line graph of a clique is a clique.
(R) The line graph of a planar graph is planar.
(S) The line graph of a tree is a tree.

Option
(A) P only
(B) P and R only
(C) R only
(D) P, Q and S only