Explanations:Chennai, formerly known as Madras, is the capital city of the Indian state of Tamil Nadu. It is located on the Coromandel Coast off the Bay of Bengal and is the fourth-largest metropolitan area in India. The city is a major cultural, economic, and educational center in South India.
The Kailasa Dam, also known as the Mettur Dam, is a masonry dam built across the Kaveri River in the state of Tamil Nadu. It is located in the Mettur Taluk of Salem District, not in Thanjavur District. The dam was constructed between 1934 and 1938 and is one of the largest dams in India. However, it is not the first dam built in India. The first dam in India was the Khadakwasla Dam, built in 1861 near Pune, Maharashtra.
The Palas dynasty was a major power in the eastern part of the Indian subcontinent, primarily ruling over the regions of Bengal and Bihar. They did not rule over the present-day state of Tamil Nadu, which was under the control of other dynasties such as the Cholas, Pandyas, and Cheras during the same period.
Therefore, the only true statement among the given options is that Chennai is the capital of Tamil Nadu. The other statements about the Kailasa Dam and the Palas dynasty are incorrect. This makes Option B the correct choice, as it only includes the true statement.