What substance would need to be added in order to reverse the reaction?

The right answer is water.

A condensation reaction can sometimes release as a product a molecule of water. We sometimes speak of synthesis by dehydration. This is, for example, the case for two monosaccharides, such as glucose or fructose, which can condense into a disaccharide (sucrose) via dehydration synthesis. The reverse reaction is then hydrolysis, the water recombining with the two hydroxyl groups, the disaccharide being converted back into two monosaccharides.

primary succession begins with a bare rock and ends with a forest secondary succession begins after a natural disaster where there is a temporary setback after a forest fire or local destruction, but the surrounding area can fill in

your spelling is a little off : ]