The whiteness of the recycled newspaper is improved by treating it with:

Explanation

A is incorrect as sodium hydroxide is not used for whitening of newspapers.B is correct as per oxides are used to whiten old newspapers.The hydrogen peroxide bleaching process results in not only increased brightness, but also in the improvement of paper physical properties. It is now well established that carboxylic acid groups are beneficial for the bonding of pulp fibers in paper and can increase the strength of paperC is incorrect as super oxides are not used to whiten newspapers.D is incorrect as normal oxides are not used to whiten newspapers.