Choices available when there are three species and two or three rates.

Correct Fit, achieved when A → B → C is fitted.

Identical kinetics as prior screen (two rates), but with the slower rate "associated" with species A rather than species B. Easily identified as incorrect by recognizing that species 'B' has been reconstructed to include negative absorbance.

Spectra acquired on a true dual beam spectrophotometer cannot have a negative absorbance.