I think that the answer is B, but I may be wrong...
Answer:
The structures are attached in file.
Hydrogen bonding and intermolecular forces is the reason for ranks allotted.
Explanation:
In determining Lewis structure, we calculate the overall number of valence electrons available for bonding. Making carbon (the least electronegative atom) the central atom in the structure, we allocate valence electrons until each atom has achieved stability.
In order of decreasing affinity to water molecules:

This is due to the fact that the
will accept protons more readily than the bicarbonate ion,
. Carbonic acid,
will not accept any more protons, hence it is the least attractive to water molecule, even though soluble.
Low pH = high acidity.
HF has a very low pH, so when added to a solution, it will lower the pH of the solution and therefore make it more acidic. So the answer should be B.