Thanks for the question, it’s a good one! Take a careful look at what the argument is stating. The author of the stimulus is making the point that the policy of nuclear deterrence has worked THUS FAR. The author isn’t making any predictions that the policy of nuclear deterrence won’t work in the future. Now take a look at what answer choice (B) tells us. It reads that the mistake the author makes is that they try to infer with certainty about what will happen in the future based on what has happened in the past. This is certainly a mistake that can be made, but as mentioned earlier, it’s not one that this author makes, since this author isn’t trying to say anything at all about the future. And so (B) isn’t the mistake the author makes, and it’s not the correct answer choice.
Hope this helps! Feel free to ask any other questions that you might have.
