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'.
Freedom fighters laboured (1)/ to the good of (2)/the poor enslaved masses.(3)/No Error (4)
The method of soil conservation in which different crops are grown in alternate rows and are sown at different times to protect the soil from rain wash is called?