40. Histologic stage is an ordinal categorical variable coded as 1-4 (higher values meaning more advanced progression of disease). Suppose this is initially modeled as a semi continuous variable in a Cox regression, resulting in the following model: In(hazard of mortaility at time t x)- In().(t)) + 0.82:11 , where x1 - 1 to 4 for the four histologic stage levels. The standard error of the slope for x1. ( SE(B, ) ) is 0.12. What does the assumption of proportional hazards mean with regards to this model? (with histologic stage as the predictor) a. The hazard of mortality is constant across the follow-up period for all 4 histologic stage groups. b. The hazard ratio of mortlality for any two histologic stage groups is constant across the entire study follow-up period. c. The In(hazard) of mortality is constant across the entire follow-up period for patients in the histologic stage-1 sample. 41