Out of curiosity I checked Wikipedia for all the mountain ranges of the world. The US has 150, Canada has 142, and the remainder of the entire world combined including Antarctica and the ocean ranges, totals 166. So maybe the US doesn't have half of the world's ranges but it has a third, and considering some of those ranges include Canada the numbers are a fair representation.
Do not see the point of including underwater mountains, if we were dealing with large Canyons for instance would we include all the underwater canyons such as Zhemchug Canyon which would demote land canyons such as Yarlung Tsangpo Grand Canyon and The USA Grand Canyon to the ouffield.
I sure love the Sierra (Sierra Nevada Mountain Range). Mainly because I live in said mountain range, but it's so great to camp in as well as many cool sights to see, such as Lake Tahoe and Yosemite. It also has quite a strong history with the California Gold Rush, including my county where John Marshall first discovered the gold leading to the rush. None of what I said is important to this quiz, I just felt like bragging about my home.
I feel like Olympic is a bit obscure and for the sake of variety there are better options, given there are already four other US ranges. Any of the other great ranges of Asia, perhaps - Karakoram or Hindu Kush? Maybe the Altai Mountains of Central Asia? Or the Zagros Mountains of Iran? The Southern Alps of New Zealand? The Drakensburg Mountains of South Africa? The Transantarctic Mountains? The Dolomites of Italy? There are many more possibilities, these were just a few that sprung to mind. Just a suggestion.
I agree, especially since many of the ranges you list are some of the highest and most beautiful in the world. As a native of the Rockies, I look down (literally) with haughty derision upon the piddly Appalachians and up with stupefying awe at the world's greater mountains.
Why no Alaskan range? The tallest in North America with Denali? I feel like they deserve a spot on the list :)