Final answer:
To find the exact percentage of U.S. adults who used alternative medicine in 2002 according to the NIH study, one needs to look up the specific study or a credible source citing the study since the reference information provided does not contain the answer.
Step-by-step explanation:
The question states that a 2002 National Institutes of Health study found that a certain percentage of adults in the United States had used some form of alternative medicine in the previous year. The options given are 30%, 36%, 42%, and 58%. The precise answer is not provided in the question nor in the given reference information. Therefore, to answer this question accurately, one would need to consult the specific NIH study from 2002 or a reliable source that cites the study's findings. In general, the use of alternative medicine can include practices such as herbal remedies, acupuncture, and chiropractic care. Such studies are integral in understanding public health trends and the broader implications for healthcare policy and practice.