What is the largest and most important river system in south america?
a.
the amazon
b.
the orinoco
c.
the rio grande
d.
the rio de la plata

A. Amazon - A major South American river. It's the second longest river in the world and one of its three major river systems, running about 4,000 miles from the west to east and emptying into the Atlantic Ocean.

3. i would say one, but one is not prime nor composite.