When she comes to work, Janelle notes that her boss has changed the chair that is at her desk after she complained that she had been having back pain. Janelle feels more satisfied and happier at work now. According to the Hawthorne Effect, what explains Janelle's increased sense of positivity at work

What explains Janelle's increased sense of positivity at work is the knowledge that her boss has paid attention to her

Explanation:

The Hawthorne effect is a kind of reactivity that involves people's altering or making changes to some aspect of their characters in response to what is being aware of observance.

We know that the Hawthorne effect can also lead to the observation being the intervention.

An instance is the Janelle's reaction (of being happy and satisfied).

The intervention here is that her boss replaced her desk with another and this triggered her satisfaction and happiness because she won't have to complain about back pain again.

i would say b. research typically uses a variety of sources