Which of the Following Is an Example of a Confirmation

Multiple Choice

Which of the following is an example of a confirmation?

A) a note thanking a coworker for her assistance on a project
B) an email telling a colleague about a book you think he'd find interesting
C) a card expressing your condolences for an employee whose family member died
D) a phone call congratulating a coworker on her promotion
E) a letter telling a customer that her claim has been registered by the company