Final answer:
Manish gained NRs. 10,000.37 after the devaluation of Nepalese currency by exchanging his American dollars back to Nepalese currency.
Step-by-step explanation:
Manish initially exchanged Nepalese currency (NRs) for American dollars at the rate of $1 = NRs. 104.28. For NRs. 2,00,000, he would get $1918.59 (calculated as 200000 / 104.28).
After four days, the Nepalese currency devalued by 5%. The new exchange rate would be the old rate increased by 5%, so $1 now equals to NRs. 109.494 (calculated as 104.28 * 1.05).
When exchanging his $1918.59 back to Nepalese currency at the new rate, Manish would get NRs. 210000.37 (calculated as 1918.59 * 109.494).
The gain incurred by Manish is the difference between what he ends up with and what he started with, which is NRs. 10,000.37 (calculated as 210000.37 - 200000). Therefore, the correct answer is (c) Gain of Rs. 10,000.37.