Which of the following statements about the physical geography of north america is true?
a. the largest tributary of the mississippi is the arkansas river
b. the ancient rock of the canadian shield covers about one fourth of canada
c. the mississippi drainage basin is the firth largest in the world
d. the most geologically active region of north america is found along the west coast or b not sure

The correct answer is - C. The most geologically active region of North America is found along the West Coast.

The West Coast of North America is by far the most geologically active region on the continent. It is part of the ''Ring of Fire''. The west has boundaries of the North American tectonic plate and the Pacific tectonic plate which causes lot of geological activity in the region. Earthquakes are a common occurrence in this part and a big rift valley stretches through California and it is getting bigger and bigger with time. The biggest volcano nowadays is found in this region, more specifically under the Yellowstone National Park in the northwestern part of the United States.