An airplanes altitude in feet during its descent for landing can be found using the function: f(x)=-300x+300,000.where x represents the horizontal distance in miles from where the plain begins its descent. it then changes to g(x)=-300x-30,500.which statement describes this change?
a: the airplane starts its descent from an altitude 500 feet higher.
b: the airplane starts its descent from an altitude 500 feet lower.
c: the airplane descends 500 feet per horizontal mile faster.
d: the airplane descends 500 feet per horizontal mile slower