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

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