A gerontocracy is a government ruled by whom?

A German geology professor makes a subterranean expedition in which 1864 classic by Jules Verne? Which German river gives its name to wine grown on its banks? What were German submarines in the two World Wars commonly called? A German woman may pluck her "Augenbrauen". What are they? A G.I. Joe figure introduced in 2000 represents one of which Native American World War II code talkers? A giant Ferris wheel graces which city's Prater park, opened to the public by Emperor Joseph II in 1766? Which giant hunk of Hollywood was born Roy Scherer Jr.? A giant sea monster turns out to be a submarine in which 1870 Jules Verne tale?