Answer:
The fault lines pull away from eachother and it breaks up into blocks r chunks which are either forced upwards or downwards. As hey move apart these chunks or blocks end up being stacked ontop of one another causing a fault block mountain as the fault lines have been blocked up. An example of a faultblock mountain are the Sierra nevada mountains in North America.
(i dont know how many marks this question is so you may not need that much information)