The correct option is 1 only. Red Sanders, scientifically known as Pterocarpus santalinus, is indeed a tree species found primarily in the forests of Andhra Pradesh, South India. However, it is not considered one of the most important trees in tropical rainforest areas; rather, it typically grows in dry deciduous forests and is valued for its high-quality timber and medicinal properties. This distinction is crucial for understanding the ecological and economic significance of the species within its specific habitat, making it relevant for UPSC Prelims in the context of biodiversity and environmental conservation.