The Harappan Civilization was discovered in the year 1922, which makes option 4 the correct answer. The Harappan Civilization, also known as the Indus Valley Civilization, was one of the most advanced ancient civilizations that existed around 2500 BCE to 1900 BCE in the Indus River Valley. Archaeologist R.D. Banerji discovered the ruins of Harappa, one of the major cities of this civilization, in 1922. The ruins of another major city, Mohenjo-daro, were discovered in 1924 by archaeologist R.D. Banerji. These discoveries shed light on the highly sophisticated urban planning, advanced drainage systems, and the use of a unique writing system of the Harappan Civilization.