Harappan civilization, also known as the Indus Valley civilization, was one of the earliest civilizations in the world that flourished in the northwestern regions of the Indian subcontinent from c. 3300 BCE to 1300 BCE. The civilization was named after the city of Harappa, one of its most prominent settlements.

The Harappan civilization was characterized by its urban planning, sophisticated drainage systems, trade networks, and writing system. Archaeologists have identified several Harappan sites across the Indian subcontinent based on their distinctive material culture and architectural features.

The correct answer to the question is option 'C', Sohagaura. Sohagaura is not a Harappan site. It is a site from the later historical period, dating back to the Mauryan period (c. 321-185 BCE).

Let's take a look at the other options and their significance:

a) Chanhudaro: Chanhudaro is a Harappan site located in Sindh, Pakistan. It was excavated in the 1930s by the archaeologist N.G. Majumdar. The site is known for its well-preserved structures, including a public bath and a granary.

b) Kot Diji: Kot Diji is a Harappan site located in the Khairpur district of Sindh, Pakistan. It was excavated in the 1950s by the archaeologist George F. Dales. The site is known for its fortified citadel, residential areas, and burial grounds.

d) Desalpur: Desalpur is a Harappan site located in the Kutch district of Gujarat, India. It was first excavated in the 1960s by the archaeologist J.P. Joshi. The site is known for its distinctive pottery, including the Desalpur Ware.

In conclusion, Sohagaura is not a Harappan site, while Chanhudaro, Kot Diji, and Desalpur are all Harappan sites.