Which of the following best explains why a spectrophotometric analysis is usually carried out at the wavelength designated as λmax for the analyte?
a) Because λmax corresponds to the highest transmittance of light through the sample, improving percent transmission readings.
b) Because at λmax the Beer–Lambert relationship becomes independent of concentration, guaranteeing linear calibration curves.
c) Because λmax provides the largest molar absorptivity (ϵ), giving the strongest absorbance signal for a given concentration.
d) Because λmax is the only wavelength that is unaffected by changes in solvent polarity or pH.