Option d is the correct answer Rai Bahadur Daya Ram Sahni was an Indian archaeologist who supervised the excavation of the Indus valley site at Harappa in 1921-22. Sahni was a trainee of John Marshall. He became the first Indian to be appointed Director-General of the Archaeological Survey of India, a position in which he served till 1935. S.R. Rao was a scientist and a former Director of the Archaeological Survey of India. He excavated the site of Lothal in present-day Gujarat which is considered a port from the Harappan civilization. Jagat Pati Joshi (J.P. Joshi) is an Indian archaeologist who discovered the Indus Valley site of Dholavira and Surkotada. Bal Krishen Thapar was an Indian archaeologist who served as the Director-general of the Archæological Survey of India from 1978 to 1981. Thapar participated in the archaeological excavations in Kailbangan, Purana Qila and Maski. Hence, Option d is incorrect. Solution: (a) Exp) Option a is the correct answer The Harappa site was first briefly excavated by Sir Alexander Cunningham in 1872-73, two decades after brick robbers carried off the visible remains of the city. Alexander Cunningham was the first surveyor of the Archaeological Survey of India (ASI). Alexander Cunningham visited the site in 1853, 1856 and 1875. But the importance of the site and the associated civilisation were not realized by him Important Tips Harappan Civilization: Sir John Marshal took over as the Director General of ASI and initiated research at the site. He realized the importance of this site. Sir John Marshal played an important role in the development of archaeology in India. Later in the 1940s, Mortimer Wheeler excavated the Harappan sites. After the partition of the Indian subcontinent, many of the Harappan sites went to Pakistan.