Who is an Investment Advisor?

Which of the following individuals need to register with the SEC under the Investment Advisers Act of 1940?
- Adam, who retired last year from a big brokerage house, but he recently started providing services to 12 clients who live in his neighborhood that he met while out golfing
- Belinda, who writes weekly investment articles for a local newspaper
- Carter, who provides incidental services as an accountant
- Diane, who provides investment services only to three large insurance companies