Correct answer: A. British
Explanation: The direct answer is A: the Ahom revolt was against British power. The Ahom kingdom was in Assam. After British expansion and administrative changes in the region, resistance arose against British control; the revolt is associated with leaders such as Gomdhar Konwar. Option A is correct because the colonial authority involved was the British. Option B, the French, is wrong because French colonial power did not control Assam in this episode. Option C, the Portuguese, is wrong because their main colonial presence was elsewhere and they were not the power challenged in the Ahom revolt. Option D, the Dutch, is also wrong because they were not the ruling colonial authority in Assam. The reasoning is to identify both the region and the ruling power: Ahom revolt in Assam, Assam under expanding British authority, therefore British. Memory cue: Ahom revolt—Assam—British—Gomdhar Konwar.