O a. Difference in Differences O. D. Regression Discontinuity Design O C. Instrumental Variable Method O d. Randomized Controlled TrialWhich empirical method does the following graph employ? a 1.00 0.90 0.80 . Local Average Logit fit 0.70 0.60 Probability of Winning, Election t+1 0.50 0.40 0.30 0.20 0.10 0.00 -0.25 -0.20 -0.15 -0.10 -0.05 0.00 0.05 0.10 0.15 0.20 0.25 Democratic Vote Share Margin of Victory, Election t b 5.00 4.50 Local Average 4.00 Polynomial fit 3.50 3.00 No. of Past Victories as of Election t 2.50 2.00 1.50 1.00 0.50- 0.00 0.25 -0.20 -0.15 -0.10 -0.05 0.00 0.05 0.10 0.15 0.20 0.25