Q. Consider the following geological discontinuities observed within the structure of the Earth:

1. Mohorovičić discontinuity
2. Gutenberg discontinuity
3. Conrad discontinuity
4. Lehmann discontinuity

Which of the following sequences correctly arranges them from the Earth’s crust to its core?
Answer: 3 → 1 → 2 → 4
Notes: The correct sequence from crust to core is: Conrad (3), Mohorovičić (1), Gutenberg (2), and Lehmann (4). Conrad discontinuity separates continental crusts, Mohorovičić marks crust-mantle boundary, Gutenberg divides mantle and outer core, and Lehmann distinguishes outer and inner core. Misconceptions regarding the Conrad discontinuity's placement are common; it does not separate mantle and outer core.