Mariana has purchased her paper from Acme Paper Company for years. When she started her business they offered the best paper for the lowest price, and they delivered it to her office with friendly service. Recently Mariana's office manager submitted a report on various prices for paper supply companies in the city. Mariana quickly skimmed the report and saw that Acme was in the same ball park price per ream, although a little more expensive than two of the companies, but they continued to deliver free of charge. Mariana decided to stay with Acme. Her decision was based on ________.
a. Intuition
b. The halo effect
c. Confirmation bias
d. None of the above

It is not intuition because Mariana consciously reasoned; the Halo effect is an overall rating (good or bad) on persons or companies based on one particular trait. In this case Mariana is only comparing the one trait of Acme she knows with other suppliers; confirmation bias, a tendency to (ab)use evidence to confirm theories, does not interfere with her decision either. I would say that her decision is partly economic, partly habit.