A(n) is an instrumental piece that typically introduces an opera.
counterpoint
oratorio
overture
program music

How does specialization enable countries to trade with one another? a country can make and sell goods affordably and buy goods that it is inefficient at making. a country can make what it chooses and sell its goods to other countries. a country can decide to buy everything it needs from other countries. a country can efficiently make goods that were once difficult to make.

The two-factor theory of emotion was proposed by

Describe at least three effects of the drug war in mexico.