Explanation:

- Gujarati: This is the correct answer. "The Story of My Experiments with Truth," the autobiography of Mahatma Gandhi, was originally written in Gujarati. Gandhi penned it as a series of articles in his journal "Navajivan" and later compiled them into a book.

- Bengali: This option is incorrect. While many of Gandhi's works were translated into various languages, including Bengali, the original language of his autobiography was not Bengali.

- English: This option is incorrect. Although the autobiography is widely available in English and many other languages, it was initially written in Gujarati.

- Marathi: This option is incorrect. Like Bengali, Marathi translations exist, but the original text was not in Marathi.