Task: Question Answering
Input (English): Question: Tα CD4 + lymphocytes: 
 Options:  <1> They are functionally cooperative with B lymphocytes and other T lymphocytes. <2> They recognize native antigens in soluble form. <3> They recognize peptides in the MHC class I context. <4> They are less abundant than CD8 + in human blood. <5> They release perforins.
Output (English): 1