Answer is B.
1. Visit a then b then e then f then we can't go back to d because we have a chance to go c or g which are still not visited so so abefdgc is wrong.
2. Visit a then b then e then f then c now all the path adjacent to c is already covered so we have to backtrack to f then go to g then d
3. Similarly a then d then g then e then b then c then f can be visited.
4. But a,d then b is not possible because we can't go back to a then b because there are nodes adjacent to explore so this is wrong