Rag pickers remove recyclable materials from the wastes such as plastic, polyethene, paper, metal wastes, rags, cardboard, glass articles etc. because all these items can be recycled and reused. For example, the paper is recycled into a usable form, metals and plastic can be melted and recycled any number of times, glass articles are recycled to form new articles as the quality of glass is not affected on recycling.
Food articles are biodegradable and hence, they are not recycled.
Hence, options A and B are correct.
So, the correct answer is 'both (a) and (b)'.