Allie Hagher Sells Ad Space for Birder's World magazine

Allie Hagher sells ad space for Birder's World magazine. She plans to call on Nancy Cole, the co-owner of Bird Watcher Supply Company, to sell her the magazine's back cover position for its special Audubon issue. Hagher knows Cole is a likely prospect for buying this ad because her referral came from Wayne Lindberg, the president of the Wild Bird Feeding Industry Association, whom Hagher was in touch with. Which of the following methods did Hagher use to find this lead?

A) Centers of influence
B) Canvassing
C) Promotional activities
D) Lists and directories