The correct answer is C. Rohtak.
Piedmont Plains are a type of plain that forms at the foot of a mountain range. They are typically characterized by their gently rolling hills and fertile soil. In India, Piedmont Plains are found in the states of Uttarakhand, Himachal Pradesh, Jammu and Kashmir, and Punjab.
The districts of Yamunanagar, Ambala, and Panchkula are all located in the state of Haryana. These districts are all located in the northern part of the state, which is a part of the Indo-Gangetic Plain. The Indo-Gangetic Plain is a vast plain that covers much of northern India and Pakistan. It is one of the most fertile regions in the world, and it is home to a large population.
The district of Rohtak is located in the southern part of Haryana. It is a part of the Aravalli Range, which is a mountain range that runs through northern India. The Aravalli Range is a relatively old mountain range, and it is not as high as the Himalayas. The Piedmont Plains are not found in the district of Rohtak because it is located in the Aravalli Range.