Task: Question Answering
Input (English): Question: Point out the correct answer in relation to the monitoring of plasma drug concentrations: 
 Options:  <1> Allergy reactions are related to the dose administered. <2> The extraction of the blood sample must be done once the balance of drug distribution in the organism has been reached. <3> The information provided by the analytical determination of plasma concentration is sufficient to perform the dosage individualization. <4> Only the immunoassay methods are valid for carrying out the analytical determination of the blood samples. <5> It must be done for all drugs that are administered intravenously.
Output (English): 2