A graph is bipartite if vertex set can be partitioned (say $V_1$ and $V_2$) such that every edge is between these two vertex set and there is no edge between vertex of same set.
So, Seeing the above graph $4,5,6,7$ have no edge among them. So, they must belong to same vertex set. and vertex $2,3,8$ have an edge with these, So they cannot belong to this set.
So, vertex can be partitioned as $\color{red}{V_1 = \big \{1,4,5,6,7\big\}}$ and $\color{red}{V_2 = \big \{2,3,8\big\}}$.
Hence option (A) is correct.
PS:) It can also be done by taking each option and seeing if there is an edge between any two vertices belonging to same set. If it is the case then move to next option. for example in option (B) there is an edge between $1$ and $3$, and they are kept in same set. So it is false option
