Answer:
a. response bias.
Step-by-step explanation:
As Rori observed the drum major's interest to her during leading the band is an example of response bias. It refers to the tendency of the people to respond to observation based on some factor other than the content. As Rori observed the drum major tendency having the interest to show off for her cannot be taken as her observations because it may differ for another observer, this type of observation regarding major interest is considered as response bias during observation.