The Indian king who warmly received Vasco da Gama when he landed at Calicut was the Zamorin. Option 1, Asaf Jah Ismail Mulk, is incorrect as he was a Nizam of Hyderabad and not related to this event. Option 2, Devaraya, is incorrect as he was a Vijayanagara emperor and not involved in Vasco da Gama`s arrival. Option 4, Krishnadevaraya, is also incorrect as he was another Vijayanagara emperor who ruled later and was not present during Vasco da Gama`s visit. Therefore, option 3, Zamorin, is the correct answer. The Zamorin was the title given to the ruling monarch of Calicut (present-day Kozhikode) during that time, and he played a significant role in the Portuguese arrival in India.