Which of the following was the leading cause of death among native americans after the arrival of europeans?

How would i answer this for an exam?

Which of the following describes what rocks usually are composed of ,

What is the general rule about surface currents? cold water flows along the ocean floor towards the equator. the east coasts of continents have cold surface currents, and the west coasts of continents have warm surface currents. seasonal and constant offshore winds create significant upwelling along the west coasts of south and north america and africa. the west coasts of continents have cold surface currents, and the east coasts of continents have warm surface currents.