A student divides a slurry containing equal amounts of \(\text{M(OH)}_2\text{(s)}\) into two samples. The student adds a small volume of concentrated \(\text{HNO}_3\text{(aq)}\) to one sample and the same volume of deionized water to the control. The metal remains in the +2 oxidation state. After stirring both samples for the same amount of time, the student filters the mixtures, dries and weighs the recovered solids, and determines the total moles of aqueous \(\text{M}^{2+}\) in each filtrate.

Which experimental result would provide the strongest evidence that the metal hydroxide precipitate dissolved after the concentrated acid was added?