What does R represent here ?

Question

Q). Let $A= (a+b)^*ab(a+b)^*,B=a^*b^*$  and  $ C=(a+b)^*$ .Then the relation between $A,B$  and $C$ is:

A). $A+B=C$

B). $A^R+ B^R =C$

C). $A^R +B=C$

D). None

Answer 1

https://gateoverflow.in//13162/plz-answer

Answer 2

R means reverse of a string.

Comments

Answer given is 'C"

How ??