A Medical Researcher Asked 50 People with Painful,arthritic Knees to Rub

A medical researcher asked 50 people with painful,arthritic knees to rub a cream that contained vitamin E on their knees for two weeks.At the end of the two weeks,she asked the subjects whether their knee pain improved,stayed about the same,or worsened during the treatment period.All 50 subjects reported improvement in their knee pain.Based on this information,which of the following statements is true?

A) The results of this study prove that rubbing a cream that contains vitamin E on arthritic knees is a good way to relieve knee pain.
B) The researcher should find a peer-review group to analyze her findings about the vitamin E-containing cream as a treatment for knee pain.
C) The results about the benefits of using a vitamin E cream for knee pain are questionable,because the researcher didn't have a control group.
D) The researcher shouldn't report her findings,until she uses a single-blind study to test the vitamin E-containing cream.