Identification of the Lehmann discontinuity is linked with which part of Earth?

Correct answer: Outer core and inner core boundary

Correct answer: B, the boundary between the outer core and the inner core. To understand this, remember that Earth is arranged in layers: crust, mantle, outer core and inner core. A discontinuity is a marked change in material or wave behaviour between two layers. The Lehmann discontinuity was identified from the behaviour of earthquake waves and indicates the transition from the liquid outer core to the solid inner core. A is incorrect because the crust–mantle boundary is the Mohorovičić or Moho discontinuity. C is not an important internal Earth boundary; the lithosphere and hydrosphere are different Earth systems. D concerns the atmosphere and is unrelated to the metallic core. Memory cue: Lehmann means the inner-core boundary; remember “Lehmann reaches the heart of Earth.”