Task: Question Answering
Input (English): Question: The traceability of an analytical method can be demonstrated: 
 Options:  <1> Carrying out the study of its selectivity. <2> By comparison with a reference method, use of certified reference materials and / or analysis of added samples. <3> Checking that the limit of detection of it is very low. <4> Evaluating the linearity of the calibration, whose most appropriate criterion is the correlation coefficient. <5> Making replicated measurements of the patterns and carrying out the analysis of the variance.
Output (English): 2