The correct answer is (a).
Brazil is the largest country in both South America and Latin America, with an area of 8,515,767 square kilometers. Argentina is the second largest country in South America, with an area of 2,780,400 square kilometers. Australia is the sixth largest country in the world, with an area of 7,692,024 square kilometers. India is the seventh largest country in the world, with an area of 3,287,590 square kilometers.
Here is a brief description of each option:
(a) Brazil, Argentina, Australia, India: This is the correct sequence of the countries in terms of area in descending order.
(b) Australia, Brazil, India, Argentina: This is not the correct sequence of the countries in terms of area in descending order. Australia is larger than Brazil, so it should be listed before Brazil.
(c) Argentina, India, Australia, Brazil: This is not the correct sequence of the countries in terms of area in descending order. Argentina is smaller than India, so it should be listed after India.
(d) India, Brazil, Argentina, Australia: This is not the correct sequence of the countries in terms of area in descending order. India is smaller than Brazil, so it should be listed after Brazil.