Which of the following statements is true of the absolute threshold?

Which of the following statements is true of the absolute threshold?
 
  A) It is determined by exposing individuals to progressively stronger stimuli until the minimum stimuli the person can detect is found.
  B) It is used to represent the minimum difference in the magnitude of two stimuli required to tell them apart.
  C) It is used to measure the intensity of sensory input by using the sensory adaptation process.
  D) It is determined by measuring the rate at which a person becomes less sensitive to stimuli of low magnitude and more sensitive to stimuli that remain the same.