Seismologists observe that primary (P) waves from earthquakes pass through Earth’s liquid outer core, whereas secondary (S) waves do not. Which explanation best accounts for this observation?
(a) P waves are transverse and therefore can shear the liquid core, whereas S waves are longitudinal and are absorbed by the fluid.
(b) Both P and S waves are longitudinal, but S waves lose energy faster and are therefore undetectable after traveling through the core.
(c) P waves are longitudinal, requiring only compressions and expansions that a fluid can support, whereas S waves are transverse and need shear rigidity absent in liquids.
(d) Both P and S waves are transverse; however, only P waves have sufficient amplitude to propagate through dense liquid iron.