Assertion A : Basin walls have to be of much grater height than dock walls. Reason R : Tidal basins are subject to fluctuations of levels due to tidal variations?

Select your answer based on the coding system given below.
A. Both A and R are true and R is the correct explanation of A.
B. Both A and R are true but R is not correct explanation of A.
C. A is true but R is false.
D. A is false but R is true.