Answer: C. They are along a plate boundary in which plates are constantly converging, causing uplift.
Step-by-step explanation:
Some mountains form when plates converge and the heavier plate sinks below the lighter plate which will cause land to be uplifted.
The Andes formed (and continue to form) as a result of plates - the Nazca and the South American Plate - converging constantly such that the western edges of the South American plate is sinking below the Andes plate and causing land to keep rising.