Explanation:

- Option 1: Rock cut architecture - This is not relevant to Kalibangan. Rock cut architecture is more associated with later Indian civilizations, like the Buddhist caves of Ajanta and Ellora.

- Option 2: Sea port - Kalibangan was not a coastal city; it was located inland, near the now-dry Ghaggar River.

- Option 3: Cotton cultivation - While the Indus Valley Civilization was among the first to grow cotton, Kalibangan is not specifically noted for this.

- Option 4: Pottery - Kalibangan is famous for a unique type of pottery with intricate designs, highlighting the artistic skills of the people.