Which among the following is not written by a sportsperson?

The correct answer is A Country Called Childhood: A Memoir.

To understand why this is the correct choice, let us look at the authors of each of the books listed in the options:
1. Open: An Autobiography is the autobiography of Andre Agassi, who is a former world No. 1 professional tennis player from the United States.
2. Unbreakable: An Autobiography is the autobiography of Mary Kom, a legendary Indian amateur boxer who is a six-time World Amateur Boxing champion and an Olympic medalist.
3. Playing It My Way: My Autobiography is the autobiography of Sachin Tendulkar, widely regarded as one of the greatest cricketers of all time.
4. A Country Called Childhood: A Memoir is written by Deepti Naval, who is a highly acclaimed Indian actress, director, and writer, and not a sportsperson.

Therefore, A Country Called Childhood: A Memoir is the only book in the list that is not written by a sportsperson.