I think the correct answer would be D. The reaction that involves an acid and a covalent base would be the reaction of sulfuric acid and water or H2SO4 + 2H2O → 2H3O+ + SO42– . The acid would be H2SO4 and the covalent base would be H2O since it is being held by covalent bonds and when in solution it will have equal amounts of OH- and H+ ions.
