What aspect of research do unobtrusive measures circumvent?

What aspect of research do unobtrusive measures circumvent?
 
  A) Unethical practices
  B) Researcher bias
  C) Researcher reactivity
  D) Unsound methods

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Why does participant action research sometimes fail?
 
  A) The participants are all trained researchers who argue.
  B) The causes investigated are often unimportant.
  C) The recommendations from the research are sometimes ignored.
  D) The issues rarely have conflicting perspectives.

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What is a key difference between action research and participant observation?
 
  A) Action research has validity checks throughout, while participant observation does not.
  B) Action research has measurable variables, while participant observation does not.
  C) Action research shares the results with others, while participant observation does not.
  D) Action research asks research questions, while participant observation does not.