Final answer:
Argentina, Mexico, South Africa, and Turkey are all members of the G20, which is a forum of the world's largest economies representing the majority of the gross world product and global trade.
Step-by-step explanation:
The question inquires about which groups the countries Argentina, Mexico, South Africa, and Turkey are all four members of the G20. The correct answer to this is option (a) Argentina, Mexico, South Africa, and Turkey.
These countries are all members of the G20, which is an international forum for the governments and central bank governors from 19 countries and the European Union. The G20 members represent the world's largest economies, comprising both developed and developing nations, and account for the majority of the gross world product (GWP) and global trade.