In biological assay, the “fish unit” method of expressing the potency of pituitary extract was used in:

Correct option is A

Correct Answer: (a) Brazil
Explanation:
→ The “fish unit” method was developed in Brazil to measure potency of pituitary extract based on fish response.
→ It quantifies hormone strength by observing ovulation/spawning rate.
Information Booster:
→ This method was mainly applied during early carp breeding experiments.
Additional Information (Other Options):
(b), (c), (d): Other countries used different assay standards.