Answer :
Answer:
D) Personal sources
Explanation:
Word of mouth promotion is by far the most effective information source and it can really influence a purchase for better or worse.
Word of mouth is simply marketing gossip, when satisfied (very positive) or unsatisfied (extremely negative) consumers tell other people about their experience with your product or service. A good personal reference is great, but a bad reference is disastrous because tend to believe on real consumer experiences more than any other type of paid advertising.