Which of the Following Persons Is Using Social Media to Act

Which of the following persons is using social media to act as a brand ambassador?

A) Noah,who posts pictures of him and his friends drinking Red Bull at a ski resort
B) Bella,who wrote an e-mail to a company to complain about poor service
C) Cathy,who clicked on the "contact us" page of a website
D) Julie,who wrote a cautionary product review on her blog
E) Paul,who inquired about a store's loyalty program