At its thickest point, how deep is the Earth's crust?

The Earth's crust reaches its maximum depth at around 100 kilometers in certain areas, particularly beneath mountain ranges and continental regions. This thickening of the crust typically occurs due to geological processes such as tectonic plate collision and mountain building, which can significantly increase the thickness of the crust in those regions.

In contrast, oceanic crust is generally much thinner, averaging about 5 to 10 kilometers in depth. The correct option highlights the significant variation in the Earth's crust, where the depth can vary widely depending on geographical location and geological activity. Understanding this variation is essential for studying geophysical phenomena and the Earth's structure.