The correct answer is: C. Hazaribagh and lower Chhota Nagpur plateau
The Damodar trough is a geological feature in eastern India that separates the Hazaribagh plateau to the north from the lower Chhota Nagpur plateau to the south. The trough is a narrow, elongated valley that is filled with alluvial sediments. It is about 200 kilometers long and 50 kilometers wide. The Damodar River flows through the trough.
The Hazaribagh plateau is a highland region in eastern India. It is located in the state of Jharkhand. The plateau is about 1,000 meters above sea level. It is a hilly region with many rivers and streams. The plateau is covered with forests.
The lower Chhota Nagpur plateau is a highland region in eastern India. It is located in the states of Jharkhand, Chhattisgarh, and Odisha. The plateau is about 500 meters above sea level. It is a hilly region with many rivers and streams. The plateau is covered with forests.
The other options are incorrect because they do not correctly identify the two plateaus that are separated by the Damodar trough.