Task: Question Answering
Input (English): Question: Which of the following analytical determinations is less useful for decision making in the follow-up and control of an HIV-infected person? 
 Options:  <1> CD4 lymphocyte count in peripheral blood. <2> Quantification of immunoglobulin. <3> Measurement of viral load. <4> Studies of HIV resistance to antiretroviral drugs. <5> Analysis of the co-receptor tropism.
Output (English): 2