Advertisement trial group
Solution 1:
This is a Focus Group.
Merriam-Webster describes it as a small group of people whose responses are studied to anticipate the larger response from the target population [rephrased].
Solution 2:
Our pilot group reacted better to the red one.
- pilot - "serving as an experimental or trial undertaking prior to full-scale operation or use: a pilot project."
1 "...all members know they are in a pilot group experience."
2 "Using a pilot group was an attempt to isolate potential problems."
3 "Running a pilot means choosing a small group of users..."