What do vienna, warsaw, london, cologne, and paris have in common? view available hint(s) what do vienna, warsaw, london, cologne, and paris have in common? they are all at the same elevation. they are all capital cities. they are all located on some of europe's major rivers. all of these cities are at the center of a metropolitan area of 10 to 20 million people. they are all located along the southern limit of pleistocene glaciation?

Let's go through the options: 

1. they are all at the same elevation.
- this is not true, as for example London's elevation is 35 meters, and Vienna's 135

2. they are all capital cities.
-false, Cologne is not a capital!

3. they are all located on some of Europe's major rivers.
This is true! for example, London - Thames, Vienna - Danube and Warsaw - Vistula

 4. all of these cities are at the center of a metropolitan area of 10 to 20 million people.
Actually none of them are, even the biggest one (London) has "only"  8 million people

5. they are all located along the southern limit of Pleistocene glaciation?
No, for example Vienna isn't! The Pleistocene glaciation was not the most extreme glaciations and it reached the north of Europe, but not the South or Central Europe