The Optimal Trade-Off Between Current Consumption Goods and Future Consumption $\frac{(1+R)}{(1+r)}$

The optimal trade-off between current consumption goods and future consumption goods is expressed as

A) MRS_C,C' = 1 + R.
B) MRS_C,C' = 1 + r.
C) MRS_C,C' = $\frac{(1+R) }{(1+r) }$
D) MRS_C,C' = 1 + i.
E) MRS_1,C' $\frac{P^{\prime} w}{P^{\prime}(1+r) }$