Which of the following statements are correct ?

(A) Index number are free from units

(B) Index number represents specialised averages in percentage

(C) $P_{01}=\frac{∑P_0}{∑P_1}×100$

(D) Index number are helpful in formulating and adopting appropriate economic policies

Choose the correct answer from the options given below :

(A), (B) and (D) Only