Since no one has ever proven that ghosts do not exist, it is reasonable to believe that ghosts do exist. The argument above is flawed because it:
Correct: B
This argument commits the fallacy of appeal to ignorance (argumentum ad ignorantiam). It concludes that something is true (ghosts exist) simply because it has not been proven false. The absence of proof against a claim does not constitute proof for the claim. Option B accurately describes this specific flaw. Option C is related but less precise; the flaw isn't just lack of evidence, but drawing a conclusion from that specific lack of evidence.