Arrange the following countries in descending order according to their population.
(A) India
(B) Indonesia
(C) Nigeria
(D) Mexico
Choose the correct option:

The correct option is (A), (B), (C), (D).

To understand why this is the correct order, we can look at the approximate populations of each of these countries:

1. India (A): Has a population of over 1.4 billion people, making it the most populous country in the list (and the world).
2. Indonesia (B): Has a population of approximately 275 million people, ranking as the fourth most populous country globally.
3. Nigeria (C): Has a population of approximately 220 million people, making it the most populous country in Africa and the sixth globally.
4. Mexico (D): Has a population of approximately 128 million people, ranking tenth globally.

Arranging these countries in descending order (from highest population to lowest population) gives:
India (A) > Indonesia (B) > Nigeria (C) > Mexico (D)

Therefore, the correct sequence is (A), (B), (C), (D).