Successor

Sir I asked you a question on 19 Nov which was:

R’s wife K expressed the wish that R, if he survived her, should have the use of her house. After K’s death her executor agreed to allow R to occupy the house a) because of K’s wishes and b) on the payment by R of $24 per year

R seeks to enforce this agreement and the Executor wishes to avoid it in order to sell the house. What is the legal position?

a) R can enforce the agreement on the basis of his deceased wife’s wishes
b) R cannot enforce the agreement because the promise to pay is not consideration
c) R can enforce the agreement because the promise of $24 per year provides consideration for it
d) R cannot enforce the agreement because the promise of $24 per year is not sufficient consideration.

1)Sir as we know the contract rights of 3rd party act, so here R can enforce the agreement in his capacity as successor?
2) Why they use word “agreement” here, word “contract” should be used na?