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