Kumarila Bhatta and Prabhakara were both scholars who belonged to the Purva-Mimamsa school of philosophy.

Option 1, Lokayata, is the school of Indian philosophy that is associated with materialism and skepticism. Kumarila Bhatta and Prabhakara did not belong to this school.

Option 2, Madhyamika, is a Buddhist school of philosophy founded by Nagarjuna. Kumarila Bhatta and Prabhakara were not associated with this school either.

Option 4, Uttara-Mimamsa, is another name for Vedanta, which is a different school of philosophy focused on the Upanishads and the Bhagavad Gita. Kumarila Bhatta and Prabhakara did not belong to this school either.

Therefore, the correct answer is option 3, Purva-Mimamsa. The Purva-Mimamsa school is known for its emphasis on the interpretation of Vedic texts, rituals, and the importance of dharma and karma. Kumarila Bhatta and Prabhakara were prominent scholars of this school and made significant contributions to its philosophy.