Your answer is Fault Block Mountains
Fault Block Mountains are created when tectonic plates break apart bed rock. If you've ever seen a picture of Yosemite National Park that enourmous rock is a Fault Block Mountain.
Best Of Luck,

Yangtze river is found in China not southeast Asia.
mekong river found in Thailand, Vietnam and many southeast Asian country so B is correct.
ganges us found in India not southeast Asia
yellow river is found in China not southeast asia
It covers around 1,200,000 square miles.
https://www.britannica.com/place/West-Siberian-Plain
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