Maura Is 10 Years Old and Is Starting to Exchange

Maura is 10 years old and is starting to exchange e-mails with her older sister, Suzanne, who is away at college.
-In one of her first e-mails, Maura includes an emoticon meaning that she is "Really happy!" The emoticon was ____.

A) ;-)
B) :-?
C) :-O
D) :-D