which of these acids is the strongest?

Among common acids, sulfuric acid is considered the strongest due to its complete dissociation and low tendency to recombine with its conjugate base. Phosphoric acid is weaker, boric acid is very weak, and 'Pyrubic acid' appears to be a misspelling of pyruvic acid, which is also an organic acid and weaker than sulfuric acid. However, strength comparisons depend on concentration and definition of 'strong' - mineral acids like sulfuric are typically stronger than organic acids.