Which statement is true? a. the rocky mountains extends from northern canada all the way through the united states. c. the mississippi river extends from northern canada all the way through the united states. b. canada and the united states share no landforms, rivers, or lakes. d. canada and the united states share no regional characteristics.

The Rocky Mountains extend from Northern Canada all the way through the United States (A) is a true statement. This is an enormous mountain range that spans two continents. Canada and the United States share many landforms, rivers, lakes, and regional characteristics. Additionally Canada and the United States share air and ocean space together which impacts their relationship in regards to trans-border pollution. 

The coast of north america , basically yes newfoundland , i would say c , good luck