$3\mathrm{.}13$ Beer$-$Lambert Law

The diagrams above show the ultraviolet absorption spectra for two compounds Diagram $1$ is the absorption spectrum of pure acetone, a solvent used when preparing solutions for an experiment. Diagram $2$ is the absorption spectrum of the solute for which the absorbance needs to be measured to determine its concentration. When the student reads the absorbance of the solution at $280nm,$ the result is too high. Which of the following is most likely responsible for the error in the measured absorbance$?$

$($A$)$ The student added too little solute to the acetone before measuring its absorbance$.$

$($B$)$ The student rinsed the cuvette with the solution before filling the cuvette with the solution.

$($C$)$ The student forgot to calibrate the spectrophotometer first by using a cuvette containing only acetone.

$($D$)$ The wavelength setting was accidentally changed from $280nm$ to $300nm$ before the student made the measurement.