In BFS, starting from a node, we traverse all node adjacent to it at first then repeat same for next nodes.
Here, we can see that only option (D) is following BFS sequence properly.
- As per BFS, if we start from $M$ then $RQN$ $($immediate neighbors of $M)$ have to come after it in any order but in $A$ here, $O$ comes in between. So, it is not BFS.
- As per BFS, if we start from $N$ then $QMO$ has to come after it in any order but in $B$ here, $P$ comes. So, it is not BFS.
- As per BFS, if we start from $Q$ then $MNOP$ has to come after it in any order but in $C$ here, $R$ comes. So, it is not BFS.
But $D$ is following the sequences.
So, D is the correct answer.