Step 1: Understanding the Question
This is a factual question asking to identify the Indus Valley Civilization (Harappan) site situated on the Sabarmati River.
Step 2: Recalling Geographical Locations of Harappan Sites
(A) Dholavira: Located in the Khadir bet island in the Rann of Kutch, Gujarat. It is not on a major river.
(B) Lothal: Located in Gujarat, between the Sabarmati River and its tributary, the Bhogavo. It is known for its large dockyard, connecting the city to the ancient course of the Sabarmati river.
(C) Mohenjodaro: Located in Sindh, Pakistan, on the banks of the Indus River.
(D) Kalibangan: Located in Rajasthan, on the banks of the Ghaggar-Hakra River.
Step 3: Final Answer
Lothal is the Harappan site located on a tributary of the Sabarmati river. Therefore, option (B) is the correct answer.