$.$ Assertion A: Limiting value of slenderness ratio for a column is less than that of a wall.

Reason R: A column can buckle around either of the two horizontal axes while a wall can buckle around only one axis. Select your answer according to the codes 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 the correct explanation of A$.$

c$)$ A is true but R is false.

d$)$ A is false but R is true.