Answer: C. The stock market now
Explanation:
The Argument target refers to the subject of the discussion in question. The speaker in question is attempting to explain why it would be a good time to buy stocks in the present which concerns the stock market today making it the subject.
The speaker does this by calling into evidence, the correlations between variables in the past and showing that with one variable ( high unemployment) currently in effect, the other variable (increasing stock prices) which it correlates with therefore has a chance of happening in the present.