Consider the following statements with reference to GATT agreement (General Agreement on Trade and Tariffs).

a. GATT was established in 1948.

b. Initially, the total number of members of GATT was 23 countries.

c. In a way WTO is the successor of GATT.

d. GATT administers all bilateral and multilateral Trade agreements.

Which of the above statement/s is/are correct?