one major evidence of global warming is ; a) all the above b) melting of polar ice c) high temperature during winter d) increased precipitation​

Explanation:

Ice cores drawn from Greenland, Antarctica, and tropical mountain glaciers show that Earth's climate responds to changes in greenhouse gas levels.

pretty sure a is right

explanation:

with the profits from the european sales, merchants purchased europe's manufactured  goods, including tools and weapons. then the merchants shipped those manufactured  goods, along with the  american  sugar and rum, to west africa where they were bartered for  slaves.