The answer is; C
In folding, when segments of Earth's crust are bent and doubled over, the sediments in between are form folds, since they are forced into a smaller space. This also occurs in converging plates boundaries.
Block Mountains occur when stress due to compression in the crust causes the hanging wall between a fault to move up relative to the footwall.
Subscript in a pair of brackets
So to balance an equation, you need to get the same amount of each type of element on either side of the --> . So you pretty much are given the subscripts in the equations and you need to add coefficients (just normal numbers) in front of any formula that needs it, keeping anything balance.

turns into

These coefficient numbers are the molar ratios, so 2 moles of KCl3 for every 3 moles of O2 so 1. 3:2
Then you can use these ratios of find out how many moles of one thing are needed if you are given the amount of another.

and use cross multiplication to solve for whatever you don't know
<span />
What i would say: The amount of gravitational potential energy an object has depends on its height and mass. The heavier the object and the higher it is above the ground, the more gravitational potential energy it holds. Gravitational potential energy increases as weight and height increases.
Hope this helps! :)