Which one of the following factors is the main source of the earth's heat?
a. sun
b. pressure
c. season
d. altitude

Venezuela’s economy relies most heavily on which of the followingvenezuela’s economy relies most heavily on which of the following? a. oil reserves in places such as the eastern llanos b. cattle ranching in the grasslands c. fertile farmland in the andean highlands d. coffee plantations in mountainous areas