Answer: B. Blind experiment
Step-by-step explanation: While conducting an experiment, experimenters may aim to eliminate factors which are very likely to cause bias and hence affect the veracity of the study. In the scenario above, the participants of the study (coworkers) were only provided with samples of the two coffee types without any of them knowing if it was the coffee they drank now or the new coffee brand. Hence, withholding such information from the participant is a technique in experimenting called blinding. Because, the information could affect the outcome and hence objective of the study as the participants were already partial towards the present coffee being consumed.