The correct option is A i>ii>iii
Intermolecular forces of attractions increases as molecular size increases. So, large amount of heat require to break strong intermolecular forces and thus boiling point increases. Here, the molecular size of (i) and (ii) is greater than (iii)
So, the boiling point of (i) and (ii) is greater than (iii).
Now comparing (i) and (ii), boiling point of isomeric haloalkanes decreases with increase in branching so boiling point of (ii) is less than (i) as former is more branched
Hence, the overall boiling point order is i>ii>iii.