Consider the following statements and select the correct answer with the help of codes given below: Assertion [A]: The work of wind as an agent of gradation is not as widespread as that of water. Reason [R]: It is effective only in the desert regions of the world where rainfall is scanty and soil particles are loose.

• 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.