The correct answer is: a) Mikir Hills
The Mikir Hills are a mountain range in the Indian state of Assam. They form the boundary between the Brahmaputra and Barak valleys. The Mikir Hills are part of the Eastern Himalayas and are a continuation of the Naga Hills. The highest peak in the Mikir Hills is Mount Saramati, which is 3,848 meters (12,625 feet) high.
The Mikir Hills are a popular tourist destination. The hills are covered in dense forests and are home to a variety of wildlife, including tigers, elephants, and deer. The Mikir Hills are also home to a number of ethnic groups, including the Mikirs, the Karbis, and the Dimasa.
The Mikir Hills are a beautiful and diverse region with a rich history and culture. They are a popular tourist destination and are home to a variety of wildlife and ethnic groups.
The other options are incorrect because they do not form the boundary between the Brahmaputra and Barak valleys.
- The Naga Hills are a mountain range in the Indian state of Nagaland. They are located to the north of the Mikir Hills and do not form the boundary between the Brahmaputra and Barak valleys.
- The Mizo Hills are a mountain range in the Indian state of Mizoram. They are located to the south of the Mikir Hills and do not form the boundary between the Brahmaputra and Barak valleys.
- The Jaintia Hills are a mountain range in the Indian state of Meghalaya. They are located to the west of the Mikir Hills and do not form the boundary between the Brahmaputra and Barak valleys.