Based on the information in "Edward Jenner and the History of Smallpox and Vaccination,” which idea best validates the claim that inoculation was an effective procedure?

The strongest support for inoculation’s effectiveness is evidence that people who received it were successfully treated. The passage’s report that the Princess of Wales’s daughters were successfully treated directly shows a positive outcome. The other choices describe who witnessed, chose, or administered inoculation, but do not state that it worked.

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