Isomorphic graphs

Question

Ans is a) 

Can anyone plz explain how G1 and G2 are isomorphic?

Answer 1

I dont think that they are. here we have G2 we have 3 cycle of degree 2 and in G1 we have only two.

Answer 2

none of the option is true actually question is wrong :)

(A) cant be option due to different cycle length

(B) G2 and G3 are not isomorphic

(C) G3 cant be simple graph because there self loop present.

(D) same as option (c)

Answer 3

none of the options are correct.
 Options (c) and (d) can be easily removed as G1 and G2 has self-loops and G3 has multiple edges. So none  of them is a  simple graph.
 Option (a) is wrong because G2 has a vertex with a self loop and G3 lacks a self-loop.
 Option (b) is wrong because the degree of the vertex with self-loop in both the graphs is not equal.

 I think the question is wrong.
 Do comment if anyone finds something about the question.

Answer 4

Clearly, the question is wrong.

a) G2 has the highest degree 5  and G3 has the highest degree 4. so we can conclude that it's not isomorphic

b)In G1 and G2, the degree of a node with self-loop is different in both graphs, so can't compare.

c) and d) can be discarded directly as none of these is simple graph due to parallel edges.