The correct answer is (b). Lothal was a Harappan city located on the banks of the Sabarmati River in Gujarat, India. It was one of the most important trading centers of the Indus Valley Civilization. The city was built around a large artificial harbor that connected it to the Arabian Sea. Lothal was also a major center of craft production, and its artisans were known for their skills in pottery, metalworking, and bead making. The city was abandoned around 1900 BC, and its ruins were discovered in 1952.
The other options are incorrect. The Narmada River is located in central India, and the Mahi River is located in Gujarat. The Bhogava River is a tributary of the Mahi River, and the Bhima River is located in Maharashtra.