The Upanishads, which are a collection of ancient Sanskrit texts, form the core philosophical concepts of Hinduism. They are believed to be written by various sages and seers known as Rishis. The most accurate answer from the given options to the question "Who wrote the Upanishads?" would be "Brahmins," as traditionally, the Brahmin caste was engaged in spiritual and scholarly pursuits, including writing religious and philosophical texts. However, this does not necessarily mean that all authors of the Upanishads were Brahmins, as the texts are a compilation of works by various authors over centuries, some of whom remain anonymous. The term "gurus" could also potentially apply as many gurus were among the learned sages of ancient India, but the choice "Brahmins" is likely more accurate in the context of the caste system and the historical class typically associated with Vedic scholarship.
