How does a large complex system like the earth system operate

The answer is:

As a result of the combination of smaller, interrelated systems

Hope this helps. 

Sequoia national park  /  inyo national forest, california, u.s. mount whitney is the tallest mountain in california, as well as the highest summit in the contiguous united states and thesierra nevada—with an elevation of 14,505 feet (4,421 m).

The answer is    d.  central highlands