Task: Question Answering
Input (English): Question: Reactivity is considered a source of error when using Observation as a method of obtaining information. Where does it come from? 
 Options:  <1> From the context in which the Observation is generated. <2> Of the observed subject. <3> Of the chosen procedure. <4> From the observer. <5> Of the type of instrument chosen.
Output (English): 2