The source for knowledge of the Harappan culture is:

Detailed Solution:

The correct answer is “Archaeological excavations”.

The primary source of information about the Harappan (Indus Valley) culture comes from archaeological excavations of ancient sites like Harappa, Mohenjo-Daro, and others.

These are inscriptions found in various parts of India are not related to the Harappan culture.

The Harappan civilization used seals with inscriptions, but the script remains undeciphered.