The correct option is C. In chemistry, a radical is defined as an atom, ion or molecule that possess an unpaired valence electron. Generally, radicals are highly reactive chemically. Examples of radicals are hydroxyl, hypochlorite, nitrate, carbonate, oxalate, permanganate, etc. Free radicals combine with one another or with single atoms to produce neutral substances. In the question given above, the two compounds given in option C have the same type of radical, which is hydroxyl radical.
Peristalsis is the wave-like motion of the walls of the alimentary canal that allow food to move along the lumen of the alimentary canal towards the posterior (anus). These waves are powered by the contraction and relaxation of the smooth muscles.
