Average incubation period of Macrobrachium rosenbergii at 28 °C:

Correct option is B

Correct Answer: (b) 20 days
Explanation:
→ At around 28 °C, the egg incubation and larval development of M. rosenbergii complete in approximately ~20 days, depending on maternal condition and water quality.
→ Temperature directly influences embryonic development rate.
Information Booster:
→ Cooler temperatures prolong incubation; optimal hatchery practices control temperature and salinity for best survival.
Additional Information (Other Options):
(a) Too short; (c),(d) indicate slower development under suboptimal conditions.