How Do Successful Professionals Often Build Personal Human Networks

How do successful professionals often build personal human networks?

A) By meeting people at professional and social situations,collecting and passing out cards,and engaging in pleasant conversation.
B) By making connections on Facebook.
C) By networking only when they are looking for a job.
D) By limiting their social contacts to only those people they know will be useful in their professional life.
E) By letting people know they are interested in business connections only.