CSV

Below you can see four files opened with a text editor. Which of them are CSV files?

File A:

First name,Last name,Age
Anna,Mackenzie,23
Paul,Smith,22
Veronica,Brown,19

File B:

Country,Capital
United Kindom,London
Russia,Moscow
USA,Washington

File C:

movies:
  1.Mr and Mrs Smith
  2.Iron Man
  3.The Devis wears Prada

File D:

{
  "country":"Russia",
  "capital": "Moscow"
}