Josie is writing a research report on the sources of vitamin C that are best for children under the age of eight.
Which of the following is a primary source that will give Josie the most reliable information?
A. a journal article on why vitamin C is necessary for children under eight
B. a college dissertation on the effects of vitamin C in children under eight
C. a medical study on nutritious foods that provide the most vitamin C to children under eight
D. a detailed survey on the foods containing vitamin C that are consumed most by children under eight