Option 1 -> Salim Ali was a renowned naturalist and ornithologist, famously called the "Birdman of India" for his pioneering work in Indian bird studies.
Option 2 -> Prafulla Chandra Roy was a distinguished chemist, known as the father of Indian chemistry and founder of Bengal Chemicals.
Option 3 -> S.S. Abhyankar was a prominent mathematician known for his contributions to algebraic geometry.
Option 4 -> Meghnad Saha was an astrophysicist famous for the Saha ionization equation in astrophysics.
Hence, Option 1: Salim Ali -> He authored "The Book of Indian Birds" and conducted extensive surveys of Indian avifauna, earning him the title "Birdman of India" -> correct