In this task, you are given a multiple-choice question about healthcare. Answer the question based on your information and classify your answers into '1', '2', '3', and '4'.
Q: 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.
A:
2