Answer:
c. F1-
Explanation:
In this chemical reaction the expression is:
HF + NaF → NaHF2
The ion that always keep the negative charge is the fluorine with a -1, if in this mixture there is more positive ions (H1+) the negative ion (F1-) will join with them.
Remember that also the Cl1- will be free, but the fluorine is more reactive than the fluorine.