Don't be surprised if we have an unusually cold winter this year. The last time we had a very cold winter was 12 years ago, and the last time before that was 12 years earlier, and the time before that was also 12 years earlier. Brace yourself for another cold one.
Which of the following would most strengthen this argument?
Something that may help explain if predictions made for 12 years periods would definitely strengthen the argument.
B does that by comparing the actual and predicted temperatures.
A. a chart showing the average temperature of winters over the last 11 years - WRONG. Average temperature might have both highest temperature values and lowest values, something that might not be strictly associated to 12th or 24th or 36th year.
B. a chart comparing the actual winter temperatures to predictions for the last 36 years - CORRECT.
C. a chart with the average winter temperatures for the last 36 years - WRONG. Average concept same as option A with larger time period.
D. weather predictions from the National Weather Center - WRONG. it would be same as what the author is predicting about the weather. So does not explain, thus does not strengthens.
E. a discussion of weather patterns that create colder winters - WRONG. Neither weakens nor strengthens the argument.
IMO answer B.