The correct option is 1 and 3. Rhynchostylis retusa, commonly known as the Foxtail orchid, is indeed an epiphytic orchid, meaning it grows on other plants for physical support but is not parasitic. Additionally, it is the state flower of both Arunachal Pradesh and Assam, reflecting its significance in the cultural and ecological landscape of these regions. The statement regarding its endemism to North-east India is incorrect, as the species can be found in various parts of Southeast Asia, showcasing the importance of accurate geographical distribution in biodiversity studies. This understanding is relevant for UPSC Prelims as it ties into broader ecological principles and regional significance in biodiversity conservation.