Which of the following is the most credible source for an essay on the use of stem cells in medical research?

A. An article that explores the ethical consequences of using stem cells in medical research found on an activist website

B. An interview with athletes who have used stem cell therapies to aid in recovery from hard-to-heal injuries.

C. A peer-reviewed scientific study on stem cell effectiveness conducted by the National Institutes of Health

D. An article in a popular magazine that explores the differences among the different types of stem cell research, such as adult stem
cells, embryonic stem cells, and amniotic stem cells.