Final answer:
The subject of this question is Geography. It is referring to a geographical feature that involves a line of rapid elevation change between the resistant rocks of the Piedmont and the softer sediments of the coastal plain.
Step-by-step explanation:
The subject of this question is Geography. It is referring to a geographical feature that involves a line of rapid elevation change between the resistant rocks of the Piedmont and the softer sediments of the coastal plain.