Whom Would You Trust as Most Reliable? Discuss the Credibility

Whom would you trust as most reliable? Discuss the credibility and authority of each individual or group listed with regard to the following issue:
You have saved up for a vacation and are considering taking a cruise on a cruise ship. You are unsure whether this would be the right kind of vacation for you and, if it is, what kind of cruise would be best for you and your budget.
a. a travel agent
b. a cruise line representative
c. a friend who has been on a cruise
d. a newspaper travel writer