When a mechanical, such as sound, reflects off a surface, what can the reflected wave tell you about the surface?

The correct answer:   [c]:   "cell phone call" .

Many archeologists and anthropologists disagree with dr. thorne's view.  thorne strongly believes that what many calls "homo erectus"  was in fact  homo sapiens,  and that they migrated out of africa almost 2 million years ago and dispersed throughout europe and asia. that's way different  from what scientists have always believed about the evolution of the species.