The correct answer is (d). The Ahom kings resisted repeated invasions by the Burmese forces.
The Ahom kingdom was an independent kingdom in the Brahmaputra valley in northeastern India from the 13th to the 19th centuries. It was founded by Sukaphaa, a Shan prince from Mong Mao, who migrated to the Brahmaputra valley in 1228. The Ahom kingdom reached its peak under the reign of Pratap Singha (1603-1641), who conquered the Kachari kingdom and extended the Ahom kingdom to the Surma valley.
The Ahom kingdom was repeatedly invaded by the Burmese forces from the 16th to the 19th centuries. The first Burmese invasion took place in 1526, and the last Burmese invasion took place in 1824. The Ahom kings successfully resisted all of these invasions, but the constant warfare weakened the Ahom kingdom and led to its eventual decline.
The Pala Empire was an Indian empire that ruled over the Bengal region from the 8th to the 12th centuries. The Delhi Sultanate was an Islamic empire that ruled over the northern Indian subcontinent from the 13th to the 16th centuries. The Mughal Empire was an Islamic empire that ruled over the Indian subcontinent from the 16th to the 19th centuries. None of these empires invaded the Ahom kingdom.