A spectrophotometer measures the transmittance or the absorbance, or both, of a particular wavelength of light after it has passed through a liquid sample. The liquid sample holder is commonly known as a cuvette. Before the transmittance or absorbance of the sample is measured, a cuvette filled only with solvent, called the blank, is placed in the spectrophotometer. Select the statement that is true for why is a blank measured before the sample. Select one: a. A blank is measured to calibrate the spectrophotometer's light source. b. There is no reason to measure a blank before the sample. c. A blank is measured to remove the signal caused by the cuvette walls and solvent. d. A blank is measured to clean the spectrophotometer.