Step 4. Tell them which one you like and ask if they still prefer the one they chose.
Step-by-step explanation:
Steps 1, 2 and 3 are absolutely right because this is the true way in which any test can be conducted. Step 4 is the one that could produce biased results. This is because, if a person like chip A but you told them that you like chip B, he can say that yes B was better.You can also manipulate people to change their results. Hence, this step can lead to biased result.
