Task: Question Answering
Input (English): Question: Transpeptidation is the step in the biosynthesis of peptidoglycan in which: 
 Options:  <1> The union of N-acetylmuramic acid with N-acetyl glucosamine occurs inside the bacterial cell. <2> The exit of the precursors from the cytoplasm to the outside takes place. <3> The binding of the precursor to the peptidoglycan occurs outside, by glycosidic bonds. <4> The binding, by means of interpeptide bridges, between peptidoglycan chains. <5> The autolisinas act forming pores in its structure.
Output (English): 4