The correct answer is option D. My science class continued on its way to the abandoned gold mine even though an unexpected thunderstorm began.
Option D is the correct choice because it effectively combines the two sentences into a complex sentence, maintaining clarity and coherence. The conjunction "even though" in Option D establishes a contrast between the unexpected thunderstorm and the persistence of the science class toward the abandoned gold mine. This construction conveys a sense of determination and highlights the resilience of the class despite facing adverse weather conditions.
Options A, B, and C also attempt to combine the sentences, but they are not as effective as Option D. Option A uses "yet," which conveys a sense of contradiction but doesn't establish a clear cause-and-effect relationship. Option B uses "which was unexpected," but the relative clause disrupts the flow of the sentence. Option C uses "meanwhile," which suggests simultaneous actions but doesn't clearly show the relationship between the thunderstorm and the continuation of the journey.
In contrast, Option D provides a smooth and coherent connection between the two events, making it the most appropriate choice for creating a complex sentence that effectively conveys the intended meaning.