The correct option is "1 and 2 only" because both oak and rhododendron are native to the Himalayan region, thriving in its varied climatic zones. Oak trees can be found in temperate forests, while rhododendrons, particularly the species Rhododendron arboreum, are common at higher altitudes, showcasing vibrant blooms. Sandalwood, on the other hand, primarily grows in tropical regions of India, particularly in the southern parts, and is not naturally found in the mountainous terrains of the Himalayas, making it an incorrect option. This knowledge helps understand the biodiversity of the Himalayan ecosystem and its climate-adapted flora.