Explanation:

- Maha Purana: A class of ancient Indian texts that gives a comprehensive narrative of the history and cosmology in Hindu theology. However, it is not the source of "Vasudhaiva Kutumbakam."

- Maha Upanishad: A part of the Upanishadic texts, it is less known than principal Upanishads but contains important philosophical themes, such as the concept of the world as a single family.

- Correct Answer: "Vasudhaiva Kutumbakam" is derived from this source.

- Rig Veda: One of the oldest sacred texts of Hinduism comprising hymns and verses, but it does not contain "Vasudhaiva Kutumbakam."

- Smriti: Refers to texts that are "remembered," including traditional writings like the epics, codes of law, and philosophical treatises, but not specifically associated with this phrase.

The theme "Vasudhaiva Kutumbakam" ('One Earth-One Family-One Future') reflects the interconnectedness of all life on Earth and is derived from the Maha Upanishad, highlighting unity and mutual care among all beings.