Martha wants to get a highly competitive internship with a state senator. she has shared this interest with her family and friends, but no one seems to have any useful contacts who can her. one day, she runs into a former classmate she has not seen for several years and learns that the classmate has a cousin who worked as the assistant campaign manager for that senator in a recent election. the classmate then offers to introduce martha to his cousin. this is an example of what concept?