JEE Main 2021 Physics question

Assertion A : If in five complete rotations of the circular scale, the distance travelled on main scale is 5 mm and there are 50 total divisions on circular scale, then least count is 0.001 cm. Reason R : Least Count = In the light of the above statements, choose the most appropriate answer from the options given below :

• (A)A is not correct but R is correct.
• (B)Both A and R are correct and R is the correct explanation of A.Correct
• (C)A is correct but R is not correct.
• (D)Both A and R are correct and R is NOT the correct explanation of A.