The statement is true.
As weird as it may sound, helium was indeed first discovered on the Sun, and after some time on Earth. The first evidence of helium was observed on August 18 1868, as a bright yellow line with a wavelength of 587.49 nanometers in the spectrum of the Sun's chromosphere. This line has been detected by a French astronomer by the name of Jules Janssen during a total solar eclipse in Gantur, India.
I would say that the Rocky Mts were the youngest of all these mountain ranges as they were created between 80-55 million years ago during the Laramide Orogeny and also they are generally much taller than the other mountain ranges mentioned here which is a characteristic of young mountain ranges and their features are sharper as they haven't been eroded the way most of these others have so have been subject to erosion for less time than the others.
Explanation:
You can try to think of it as a picture in your head.
Answer: plateaus.
Plateau is a large extension of high and quite flat land.
Studying the new world made them see that the coastlines on each side of the Atlantic are similar.
Hope this helps!