Which Statement Best Reflects the Concept of an Absolute Threshold

Which statement best reflects the concept of an absolute threshold?

A) Jerry is listening to his iPod and smells pizza burning in the oven.
B) Delilah is lying in her bed trying to fall asleep.As she is about to drift off,she is not certain but thinks she hears a car door close outside.
C) Deanna can't tell if the new paint she used is different from the original color.
D) As Jenny gets used to the buzzing of the engines,flying on a plane doesn't seem as scary.