Which of the following best represents an absolute threshold? a. A guitar player knows that his D string has just gone out of tune. b. A photographer can tell that the natural light available for a...

Which of the following best represents an absolute threshold?

a. A guitar player knows that his D string has just gone out of tune. b. A photographer can tell that the natural light available for a photograph has just faded slightly. c. Your friend amazes you by correctly identifying unlabeled glasses of Coke and Pepsi. d. A cook can just barely taste the salt she has added to her soup. e. Your mom throws out the milk because she says the taste is “off.”