Explanation
Correct answer: A.
Choice A is the best answer. "Ascended" is in the simple past tense. Since Kamehameha became king in the past, this makes the most sense.
Why the other choices are wrong
Choice B
Choice B is incorrect. "Will ascend" is in the future tense, but we wouldn’t know about Kamehameha III’s ascent if it hadn’t happened yet. The information in the sentence, as well as the tense of other verbs, tells us that the events described happened in the past.
Choice C
Choice C is incorrect. "Ascends" is in the simple present tense. However, the information in the sentence, as well as the tense of other verbs, tells us that the events described happened in the past.
Choice D
Choice D is incorrect. "Is ascending" is in the continuous present tense, which we use to show that something is ongoing, but this doesn’t make sense here—the information in the sentence, as well as the tense of other verbs, tells us that the events described happened in the past.