A student uses a spectrophotometer to construct a standard calibration curve of absorbance versus concentration for \(\text{Co(NO}_3\text{)}_2\text{(aq)}\) at \(\lambda = 510\text{ nm}\). All standard solutions are measured using a rectangular cuvette in the standard orientation shown, where the path length is \(1.00\text{ cm}\).

When measuring the absorbance of a \(\text{Co(NO}_3\text{)}_2\text{(aq)}\) solution of unknown concentration, the student accidentally places the cuvette in the rotated orientation, so the path length of the light beam is \(0.50\text{ cm}\). The student then uses the calibration curve to determine the concentration of the unknown solution without correcting for the change in orientation.

Which of the following correctly predicts the effect of this error on the calculated concentration of the unknown solution, and provides the correct justification?