Among the following which acts as the strongest acid in reaction where nitric acid behaves like a base is ____ ?

Following is the reactionHNO3+HF→F2+H2O+NOFAs a non-aqueous solvent HF ionises in the following manner more easily as compared to other hydra acids.2HF⇋HF2-+H+Due the ease of the above step, nitric acid can be protonated easily and so it can act as a base.