Question

how long is the amazon river? select the best estimate. 6,400 kilometers 6,400 millimeters 6,400 meters 6,400 centimeters

Explanation:

The Amazon River is one of the longest rivers in the world. Kilometers are a suitable unit for measuring the length of a large - scale river. Millimeters, centimeters, and meters are too small units for measuring the length of a river like the Amazon. 1 kilometer = 1000 meters, 1 meter = 100 centimeters, 1 centimeter = 10 millimeters.

Answer:

6,400 kilometers