The correct option is (c).
Explanation
The conversion of waste into manure involves the process of decomposition or composting, where microorganisms (bacteria and fungi) break down complex organic matter into simpler substances. This process is strictly limited to biodegradable materials. Non-biodegradable substances possess molecular structures that natural microbial enzymes cannot break down.
Statement-wise Analysis:
- 1. Vegetable peels: Correct. Vegetable peels are organic biological waste. They consist of carbohydrates, proteins, and fibers that are easily metabolized by microbes during the composting process to form humus or manure.
- 2. Polythene bags: Incorrect. Polythene is a synthetic polymer made of long chains of ethylene monomers. It is non-biodegradable because soil microbes lack the specific enzymes required to break the strong carbon-carbon bonds in this synthetic plastic.
- 3. Broken plastic toys: Incorrect. Similar to polythene bags, plastic toys are made from synthetic polymers (such as polypropylene or PVC). These materials are resistant to microbial action and do not decompose into manure.
- 4. Dry leaves: Correct. Dry leaves are natural plant residues containing cellulose, hemicellulose, and lignin. Soil microorganisms, particularly fungi and bacteria, effectively degrade this organic matter, converting it into nutrient-rich manure.
Key Takeaway:
Microbial action can only convert biodegradable organic waste (such as plant and animal residues) into manure; synthetic non-biodegradable materials like plastics and polythene remain unaffected by composting processes.