Which of the following mountain ranges is made of rock that is believed to be over four million years old?
a. the laurentian mountains
b. the st. elias mountains
c. the rocky mountains
d. the cascade mountains

a. the laurentian mountains

Explanation:

The Laurentian mountain range is a range that is found along the southern Quebec is the Canada province and is located between the north of the st. alurance river. It has the highest point of about the 1166 meters. And crosses the us border to the south, and the Appalachians mountains are a part of the laurinaria mountain system. Some extensions can be also found in the central Ontario. They are about 540 million years rocky mountain range of the world, and thus are part of the Grenville orogen.