Answer : 1. "International Law"
Explanation :

Ved Prakash Nanda, who received the Padma Bhushan award on 20 March 2018 in the field of literature and education, died on 1 January 2024. He was a distinguished professor of international law at the University of Denver, Colorado, indicating that his primary academic expertise was in international law. His significant contributions to this field were recognized through the establishment of the Veda Nanda Center for International and Comparative Law at the University of Denver, which emphasized his profound influence and expertise in international law.