To answer this question, we need to have some knowledge about the family of Mahatma Gandhi.
Option A) Only child - This option is incorrect because Mahatma Gandhi had siblings.
Option B) Eldest child - This option is incorrect because Mahatma Gandhi was not the eldest child in his family.
Option C) Second child - This option is incorrect because Mahatma Gandhi was not the second child in his family.
Option D) Youngest child - This option is correct because Mahatma Gandhi was the youngest child in his family.
The correct answer is D) Youngest child. This option is correct because Mahatma Gandhi was the youngest child in his family.