The correct answer is: Both A and R are true but R is not a correct explanation of A.
The Sultans may not have been too eager to encourage large scale conversion to Islam because they would lose revenue from the jizya tax, which was paid by non-Muslims. However, this is not the only reason why the Sultans may have been reluctant to encourage conversion. They may also have been concerned about the potential for social unrest if a large number of people converted to Islam. Additionally, they may have wanted to maintain a balance of power between Muslims and non-Muslims in their empire.
The reason (R) is not a correct explanation of the assertion (A) because it does not take into account all of the possible reasons why the Sultans may have been reluctant to encourage conversion.