Explanation:

H.V.R. Iyengar was the Secretary to the Constituent Assembly. He was among the exceptional members of the Indian Civil Service (ICS). He also served as the sixth Governor of the Reserve Bank of India from 1 March 1957 to 28 February 1962. Hence, pair 1 is not matched correctly. • Prem Behari Narain Raizada was the calligrapher of the Indian Constitution. The original constitution was handwritten by him in a flowing italic style. The calligraphy of the Hindi version of the original constitution was done by Vasant Krishan Vaidya and elegantly decorated and illuminated by Nand Lal Bose. Hence pair 2 is matched correctly. • Sir Benegal Narsing Rau (1887-1953) was appointed as the constitutional advisor (Legal advisor) to the Constituent Assembly. He served as an Indian Civil Service officer, a jurist, a diplomat, and a statesman of great repute. He was also India’s Representative to the United Nations Security Council between 1950 and 1952. Hence, pair 3 is matched correctly. • The drafting committee of the Constitution was appointed on August 29, 1947, with Dr. B.R. Ambedkar as the Chairman. Surendra Nath Mukherjee was the chief draftsman of the constitution in the Constituent Assembly. Hence, pair 4 is not matched correctly.