OG详解-OG6 文法 Q19

Choice C is the best answer. The convention being tested is the coordination of main clauses within a sentence. This choice uses a semicolon in a conventional way to join the first main clause (“Clear… through”) and the second main clause (“wax…through”).
Choice A is incorrect because it results in a comma splice. Without a conjunction following it, a comma can’t be used in this way to join two main clauses. Choice B is incorrect because it results in a run-on sentence. The two main clauses (“Clear…through” and “wax…through”) are fused without punctuation and/or a conjunction. Furthermore, it results in a confusing and illogical sentence that suggests clear glass allows light to pass through wax paper, which doesn’t make sense in this context. Choice D is incorrect because when coordinating two longer main clauses such as these, it’s conventional to use a comma before the coordinating conjunction.