Are the particles in a solid in constant motion, or are they "frozen in place? "

The molecules are frozen in place but still vibrate

Particles that are in a solid are tightly locked in place so the answer to your question would be  "Frozen in place"

They did not study the continental drift

The question is incomplete. complete question is attached belowanswer: correct answer is option b  i.e.  solid particles  reason: filter paper has small pores, through which smaller particles can pass through. however, solid particles  have relatively larger size. hence, they are least likely to pass through.