One remedy for a deficiency of vitamin B12 for the elderly is a regular injection of this important nutrient. The vitamin B12 injection dose depends on factors such as gender and age.
Hydrogen bonds happen in alcohols. As a matter of fact, any molecule that contains a hydrogen atom attached to an atom of nitrogen or oxygen is capable of such a bond. Ethanol is one such alcohol that features hydrogen bonds. Ammonia is an example of hydrogen bonding. In the case of ammonia, however, the hydrogen bond happens to be relatively weak.
I know that hydrogen bonding generally only works with hydrogen being attracted to a nonbonding pair on a very electronegative atom (N,F,O and Cl). So only A,B, and C can be the answer. The answer turns out to be B, but I really thought it would be A since flourine is the most electronegative.