Misc: what are the three great pyramids of egypt?

Questions

Because of heavy---------- , Julius Caesar banned all wheeled vehicles from Rome during daylight hours.?

Because of heavy traffic congestion, Julius Caesar banned all ---------- from Rome during daylight hours.?

Because of heavy traffic congestion, Julius Caesar banned all wheeled vehicles from Rome during---------- .?

Because of the ---------- content of the Dead Sea, it is difficult to dive below its surface.?

---------- are chief export of Nauru, an island nation in the Western Pacific.?