The correct answer is: a) Maibong.
The Dimasa Kingdom was an ancient kingdom that existed in the Brahmaputra Valley in northeastern India. The kingdom was founded in the 7th century by the Dimasa people, who are an ethnic group native to the region. The Dimasa Kingdom reached its peak in the 12th century, when it controlled a large territory that included parts of present-day Assam, Nagaland, and Manipur. The kingdom declined in the 13th century, and it was eventually conquered by the Ahom Kingdom in the 16th century.
The capital of the Dimasa Kingdom was Maibong, which is located in present-day Assam. Maibong was a major center of trade and culture during the Dimasa Kingdom. The city was also home to a number of important temples and monasteries.
The other options are incorrect because they are not the capital of the Dimasa Kingdom. Dimapur is the capital of Nagaland, Guwahati is the capital of Assam, and Tezpur is a city in Assam.