Let, D = <A, R> be a directed graph or digraph,then D = <A , R > is a subgraph if ___________

Let, D = <A, R> be a directed graph or digraph,then D = <A , R > is a

1.	Let, D = <A, R> be a directed graph or digraph,then D = <A , R > is a subgraph if ___________
A.	A A and R = R (A x A )
B.	A A and R R (A x A )
C.	R = R (A x A )
D.	A A and R R (A x A )
Answer» B. A A and R R (A x A )