The correct option is "1 and 2 only" because both the Ajanta Caves and the Lepakshi Temple are renowned for their exquisite mural paintings that depict narratives from Buddhist and Hindu traditions, respectively. The Ajanta Caves, dating back to the 2nd century BCE to 6th century CE, are celebrated for their intricate frescoes that illustrate Jataka tales, while the Lepakshi Temple, built in the 16th century, showcases stunning wall murals portraying various mythological themes. In contrast, the Sanchi Stupa primarily features stone carvings and sculptures rather than murals, thus highlighting the significance of these two monuments in the study of ancient Indian painting styles and their cultural context, which is pivotal for understanding India's rich artistic heritage in UPSC examinations.