The correct answer is: A. Purbi Singhbhum
Purbi Singhbhum is the district of Jharkhand with the highest production of paddy crop. In 2020-21, the district produced 2.5 million tonnes of paddy, which was about 25% of the total production of paddy in Jharkhand. The other districts of Jharkhand with significant production of paddy are Gumla, Dumka, and Ranchi.
Gumla is the second largest producer of paddy in Jharkhand, with a production of 1.5 million tonnes in 2020-21. Dumka is the third largest producer of paddy in Jharkhand, with a production of 1 million tonnes in 2020-21. Ranchi is the fourth largest producer of paddy in Jharkhand, with a production of 0.5 million tonnes in 2020-21.
The high production of paddy in Purbi Singhbhum is due to a number of factors, including the availability of fertile land, a favorable climate, and the use of modern agricultural practices. The district has a long history of rice cultivation, and farmers in the district have developed a deep understanding of the crop and its cultivation. The climate in Purbi Singhbhum is also ideal for rice cultivation, with warm temperatures and abundant rainfall. In addition, farmers in the district have adopted modern agricultural practices, such as the use of high-yielding varieties of rice, the use of fertilizers, and the use of irrigation. These factors have contributed to the high production of paddy in Purbi Singhbhum.