S waves, or secondary seismic waves, can only travel through solid materials, making soil the correct choice among air, magma, soil, and water.

S Wave Basics

S waves are transverse seismic waves generated by earthquakes that move material perpendicular to their direction of travel. These waves require a solid medium to propagate because solids provide the shear strength needed for their side-to-side motion. Gases like air and liquids like water or magma lack this rigidity, so S waves cannot pass through them.

Analyzing the Options

Here's a breakdown of each option based on their physical states:

Object| State| Can S Wave Travel Through?| Reason
---|---|---|---
Air 1| Gas| No| Gases have no shear strength; S waves dissipate.
Magma 1| Liquid (molten rock)| No| Liquids flow and cannot sustain shear deformation. 5
Soil 13| Solid (particles with cohesion)| Yes| Behaves as a solid medium for wave propagation.
Water 3| Liquid| No| Similar to magma, lacks rigidity for S waves.

Why This Matters in Earth Science

This property helped scientists confirm Earth's outer core is liquid—S waves don't reach the opposite side of the planet from earthquakes. Soil, as a porous solid, allows S waves to travel effectively, unlike fluids. Recent discussions on geology forums echo this, noting S waves' behavior in sedimentary layers like soil.

TL;DR: Soil is the only solid option here, so S waves travel through it.

Information gathered from public forums or data available on the internet and portrayed here.