Which of these mountain ranges is the newest geologically speaking? a great smoky mountains b rocky mountains c blue ridge mountains d green mountains

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. 

"pacesetter of the south," comma inside the quotes

Answerglycogen;