C LANGUAGE ONLY MUST USE RECURSION

You have an index card with the letter A written on one side, and B on the other. You want to see ALL of the possible ways the card will land if you drop it n times. Write a recursive function that prints each session of dropping the cards with A's and B's. For example of you drop it 4 times in a given session, all possible ways to drop it are as follows:

AAAA

AAAB

AABA

AABB

ABAA

ABAB

ABBA

ABBB

BAAA

BAAB

BABA

BABB

BBAA

BBAB

BBBA

BBBB