Which Statement Best Characterizes the GATT's Most-Favoured Nation Clause

Which statement best characterizes the GATT's most-favoured nation clause?  

A)  Tariff reductions that are granted by a member of GATT to imports from one country apply only to that country. 
B)  Tariff reductions that are granted by a member of GATT to imports from one country are extended only to certain favoured members of GATT. 
C)  Tariff reductions that are granted by a member of GATT to imports from one country are extended to all other members of GATT. 
D)  Tariff reductions that are granted by a member of GATT to imports from one country must be matched by equivalent quota reductions.