For maximum path length , we need to consider the maximum chain length possible..
So if we start from 2 we get chains as : 2 -- 4 -- 8
2 -- 6 -- 12
2 -- 4 -- 12
if we start from 3 we get chains as : 3 -- 6 -- 12
3 -- 9
if we start from 3 we get chains as : 5 -- 10
Vertices 7 and 11 remain disconnected..
Moreover the graph will be a directed one because x divides y is only one way
Assuming finite answer , hence the correct answer should be 2..[May be 3 -- 6 -- 12 etc ]