Final answer:
The most indicative evidence of a treatment's effectiveness in the scientific method is that the survival times are better compared to a control group receiving standard treatment, as this provides objective data for evaluation.
Step-by-step explanation:
In the context of the scientific method, the evidence most indicative of the effectiveness of a treatment would be "c) that the survival times of the patients were better than those of equivalent patients being treated with conventional therapies." This is because it directly measures the treatment's impact by comparing the experimental group (patients who received the new treatment) with a control group (patients who received standard treatment). Unlike testimonials from medically qualified people or the willingness of patients to pay for a treatment, which are subjective, survival times provide objective data to evaluate the effectiveness of a treatment. Furthermore, the patients' right to select their own treatment does not serve as evidence of a treatment's effectiveness. Therefore, strong research generally requires comparing two groups and assessing statistically significant differences in outcomes, as this is a robust form of evidence in scientific studies.