In a cross sectional study of bicycle helmet use, authors were interested in assessing neighborhood socio-economic status (as measured by percentage of school children receiving free or reduced-fee lunches at school) and percentage of bicycle rider wearing a helmet. If the assumptions of the test were met, what is the appropriate statistical test to perform:
a. two independent sample t-test
b. Wilcoxon sign-rank test
c. correlation analysis
d. chi-square one-sample test of the variance
e. none of the above