The correct answer is: C. East Champaran and Darbhanga.
Bihar is one of the leading fish producing states in India. The state has a long coastline and a number of rivers, which provide a conducive environment for fish breeding and cultivation. The leading fish producing districts of Bihar are East Champaran and Darbhanga. These districts account for a significant share of the state’s total fish production.
East Champaran is the largest fish producing district in Bihar. The district has a number of large reservoirs and ponds, which are ideal for fish farming. The main fish species cultivated in East Champaran are carp, rohu, and pangasius.
Darbhanga is the second largest fish producing district in Bihar. The district has a number of rivers and canals, which are also ideal for fish farming. The main fish species cultivated in Darbhanga are carp, tilapia, and catfish.
The other options are incorrect because they do not include East Champaran or Darbhanga. Madhubani is a district in Bihar, but it is not one of the leading fish producing districts. Muzaffarpur is also a district in Bihar, but it is not one of the leading fish producing districts.