What key event united the greek city-states to a greater degree than they had been before? a the establishment of a constitution by solon b the development of democracy in athens c the fighting of the persian wars d the formation of the delian league

Ifound this on google i hope this you “the correct answer is: the czech republic's decision in 2003 to join the european union indicated that the czech republic was willing to forge economic ties with other nations. the european union is a political and economic organism composed by 28 states located mainly in european lands.”

Answer they are produced by collision of tectonic plates;