Archeologists have unearthed the tombs of thousands of workers. The author suggests that these tombs belonged to the workers who built the pyramids. What reasoning does she use to support this claim?

You could argue with the fact that a common worker was allowed their own burial tomb. Back in ancient Egypt few were rich enough to have a Tomb built. Also the tomb seams to be a graveyard, which implies that this is a place specifically designated for the dead, which were usually not tombs but in places closer to town.