Which is the correct sequence in context with the least biodegradable to most biodegradable material?
A. Bones, Plastic, Paper, Metal Can
B. Paper, Metal Can, Bones, Plastic
C. Plastic, Metal Can, Bones, Paper
D. Plastic, Bones, Paper, Metal Can

Hint: Things which can be decomposed by microbes will be called biodegradable, and things which can not be decomposed by microbes are termed non-biodegradable materials. Microorganisms may decompose other living matter. But microorganisms can not sever stronger chemical bonds between plastics.

Complete answer:
Decomposition is a mechanism by which organic materials such as wood, dead animals and paper get broken down into smaller organic compounds. To decompose anything, it is buried in the soil where bacteria will break it down. Organic decomposed content is then recycled. Decomposed organic compounds offer food for plants, improve soil quality and feed other living organisms. Plastics and metal containers are not decomposed by microorganisms, making them the least environmentally friendly (Biodegradable). The proteinaceous portion of the bone is biodegradable, while the mineral-based portion is non-biodegradable. The key components of paper are cellulose plant material and the rest of plant materials are biodegradable.

Hence, the correct answer is option (C).

Additional information:
The worry with decomposing plastic is that plastic is not the organic material. Most of the plastics that are in use today are made of polyethylene terephthalate (PET for short) and are nearly indestructible. It is almost difficult to decompose PET plastics since most bacteria can not break them down. The sun's UV light can break down plastic, but it takes a long time.

Note: On an industrial scale, we can handle biodegradable waste by either composting or anaerobic digestion (AD). For fibrous materials, composting is more appropriate. For wet wastes and sludges that quickly degrade, AD is more fitting. We must comply with stringent guidelines whether we handle food waste containing meat and fish, or other animal by-products.