Task: Question Answering
Input (English): Question: A classification of gas chromatography detectors commonly found in the literature divides them into concentration and mass detectors, destructive and non-destructive, integral or differential and universal or selective. According to this classification: 
 Options:  <1> The thermal conductivity detector is a selective detector. <2> The flame ionization detector responds to the concentration of the analyte. <3> The thermal conductivity detector responds to the concentration of the analyte. <4> The phosphorus and nitrogen detector (NPD) is a universal detector. <5> The thermocalorimeter detector is of the differential type.
Output (English): 3