Identify the correct use of commas in a list: ‘We bought apples oranges bananas and grapes.’

A. We bought apples, oranges, bananas, and grapes.
B. We bought apples oranges, bananas, and grapes.
C. We bought apples, oranges bananas and grapes.
D. We bought apples oranges bananas and grapes.

Answer: We bought apples, oranges, bananas, and grapes.