Pheretima posthuma:
Pheretima posthuma, commonly known as the Indian earthworm, is a species of earthworm found in India. It is widely studied for its ecological importance and its role in soil fertility. Several scientists have contributed to the understanding of Pheretima posthuma, including K.N. Bahal.

K.N. Bahal:
K.N. Bahal was a famous Indian scientist who made significant contributions to the field of earthworm research. He was a professor at Banaras Hindu University (BHU) and conducted extensive studies on Pheretima posthuma.

Research on Pheretima posthuma:
Pheretima posthuma has been a subject of interest for scientists due to its ecological significance and its role in soil fertility. The earthworm plays a crucial role in the decomposition of organic matter, nutrient cycling, and soil structure improvement.

Ecological Significance:
The Indian earthworm enhances soil fertility through its burrowing activity, which improves soil structure and helps in nutrient cycling. It consumes organic matter such as dead leaves and converts them into nutrient-rich castings, also known as vermicompost. These castings are highly beneficial for plant growth and contribute to the overall health of the soil.

Soil Structure Improvement:
Pheretima posthuma's burrowing activity creates channels in the soil, allowing air and water to penetrate deeper. This improves soil aeration and drainage, creating a favorable environment for plant roots. The earthworm also helps in the formation of aggregates, which enhance soil structure and stability.

Nutrient Cycling:
The earthworm ingests organic matter and breaks it down in its digestive system. The organic matter is partially decomposed and mixed with soil, resulting in the release of essential nutrients like nitrogen, phosphorus, and potassium. These nutrients are then available for uptake by plants, promoting their growth and productivity.

Conclusion:
K.N. Bahal, a renowned Indian scientist, conducted significant research on Pheretima posthuma, the Indian earthworm. His studies contributed to our understanding of the ecological importance of this species, including its role in soil fertility, nutrient cycling, and soil structure improvement. Pheretima posthuma continues to be a subject of interest for scientists, as it plays a crucial role in maintaining healthy ecosystems and sustainable agriculture.

Famous Indian Scientist ... Prof. Kram Narayan Bhal ( K.N.Bhal ) ... of Lucknow University .... published a memoir on Indian earthworms
... Pheretima posthuma .... in 1926 ... He was awarded with .... Joy Govind law memorial gold medal in ... 1942 ... for notable research in .... Asiatic Zoology ... Hence , option C is correct ...