45. Now, suppose another Cox regression is fit with a categorical version of histologic stage as its predictor yielding the following results: In(hazard of mortaility at time t x)- In(). (t)) + 1.621 + 2.212 + 3.123, where x, -1 for patients with stage 2 (and 0 if not), x2 =1 for patients with stage 3 (and O if not), and x3 =1 for patients with stage 4 (and 0 if not). The standard errors for the slopes of x1, x2, and x3 are 1, 1, and 1 respectively. Based on this model (with histologic stage as multil-categorical), what is the estimated hazard ratio of death for patients with a histologic stage of 4 compared to patients with a histologic stage of 1? a. -3.1 b. 3.1 c. 0.05 d. 22.1 46