Task: Question Answering
Input (English): Question: The calibration curves used in chemical analysis: 
 Options:  <1> They represent the response of an analytical method to unknown concentrations of analyte. <2> They use standard samples that contain the solvent used in the analytical method, but without analyte. <3> They use a standard solution that allows knowing the response of the analytical method to the interfering species that exist in the reagents. <4> They are constructed by preparing samples of known analyte concentration (standards) and determining the response of the analytical procedure to these standards. <5> They are constructed using samples of unknown analyte concentration and measuring the response of the analytical procedure to them.
Output (English): 4