Which of the Following Statements About the General Agreement on Tariffs

Which of the following statements about the General Agreement on Tariffs and Trade (GATT) is true?

A) In practice,it has done away with nonconforming tariffs.
B) Under GATT,countries are prohibited from implementing the concept of national treatment.
C) Under GATT,once a good has been imported,it must be treated just as domestic goods are treated.
D) It discourages offering the same reduced tariff to all World Trade Organization members.