Yet another study appearing in the New England Journal of Medicine reports the results of a randomized clinical trial conducted in China, designed to compare the efficacy of two treatments for hypertension in older adults. With regards to study design, the researchers report: \"In this multicenter, randomized, controlled trial, we assigned Chinese patients 60 to 80 years of age with hypertension to a systolic blood-pressure target of 110 to less than 130 mm Hg (intensive treatment) or a target of 130 to less than 150 mm Hg (standard treatment). The primary outcome was a composite of stroke, acute coronary syndrome (acute myocardial infarction and hospitalization for unstable angina), acute decompensated heart failure, coronary revascularization, atrial fibri-Iation, or death from cardiovascular causes." \"Of the 9624 patients screened for eligibility, 8511 were enrolled in the trial; 4243 were randomly assigned to the intensive-treatment group and 4268 to the standard-treatment group" Enrolled patients were follow-up for up to one year after randomization. The following KaplanMeier was included to show the primary findings from the study: 0.10- 0.8- 0.08 0.06- 0.6- Standard treatment Cumulative Incidence 0.04- 0.4- 0.02- Intensive treatment 0.2- 0.00+ 0 6 12 18 24 30 36 42 48 0.0- 0 12 18 24 30 36 42 Months since Randomization No. at Risk Standard treatment 4268 4147 4070 4000 3938 3849 3664 1200 Intensive treatment 4243 4174 4109 4039 3970 3867 3694 1234 Figure 3. Cumulative Incidence for the Primary Outcome. The Cox proportional hazard model used to quantify this association is as follows: In(hazard of the primary outcome at time t) = In(1.(t)) + -0.30x115. 1 poil Suppose the researchers are interested in whether the effect of the \"Intensive Treatment\" (compared to \"Standard Treatment\" ) is modied by smoking history (3 categories). What should they do to investigate this possibility of effect modication? a. Nothing. As this is a randomized trial, the potential for effect modification is minimal. b. Compare the unadjusted hazard ratio (and 95% CI) of the primary outcome for \"Intensive Treatment" to "Standard Treatment" to the smoking history adjusted hazard ratio (and 95% CI) of death for \"Intensive Treatment" compared to \"Standard Treatment". c. Estimate hazard ratios of the primary outcome (and 95% Cls) for \"Intensive Treatment" compared to \"Standard Treatment" separately for each smoking history category. Compare these smoking history category-specific results. d. Plot separate Kaplan-Meier curves estimating cumulative survival for each smoking history category