Definition: In this task, you are given a multiple-choice question about healthcare. Answer the question based on your information and classify your answers into '1', '2', '3', and '4'.
Input: Question: In the quantitative analysis by gas chromatography, to minimize the uncertainties that are introduced with the injection of the sample, the flow velocity and the variations in the conditions of the columns is used: 
 Options:  <1> Manual estimation of chromatographic peak heights. <2> The normalization of the areas. <3> The method of standard additions. <4> An external calibration <5> The internal pattern method.
