Amount of mahua oil cake used in the pond to kill unwanted fishes:

Correct option is C

Correct Answer: (c) 250 ppm
Explanation:
→ Mahua oil cake acts as a botanical piscicide; 250 ppm effectively eradicates predatory and weed fishes before stocking ponds.
→ It decomposes into organic fertilizer enriching pond soil.
Information Booster:
→ Safe because toxicity decreases rapidly after decomposition.
Additional Information:
(a), (b): Too low to kill unwanted fishes.
(d) 2500 ppm: Excessively high and can harm pond ecology.