Task: Question Answering
Input (English): Question: After antigenic recognition, the T cell receptor transmits an activation signal through: 
 Options:  <1> CD3 and chain . <2> Ig and Ig. <3> TAP1 and TAP2. <4> RAG1 and RAG2. <5> Determining regions of complementarity 1 and 2.
Output (English): 1