In the following question, some part of the sentence may have errors. Find out which part of the sentence has an error and select the appropriate option. If a sentence is free from error, select 'No Error'.
Everybody knows(1)/ that Bhutan is the most peaceful(2)/ of all other countries of the world.(3)/ No Error(4)
If hiring an extra worker increases a factory's output from 1000 to 1200 units per day, but the factory has to reduce the price of its product from Rs. 25 to Rs. 24 per unit to sell the additional output, the marginal revenue product of the last worker is