An educational researcher wanted to test and compare the impact of three different learning environments on children's confidence with math. She randomly selected 24 students and then randomly divided this group into three subgroups: a 'Placebo' group who did a math test in their usual classroom environment; an 'Outdoor' group who did a math test in an outdoor setting within the school grounds; and a 'Chill out' group who did a math test in a 'chill out' space within the school, that had dimmed lighting, music, and casual seating. The children spent one hour within their settings, and their math scores were recorded at the end of the test.
What sort of statistical test should be conducted on this data?
a. Repeated-measures ANOVA.
b. One-way ANOVA.
c. Correlation.
d. Multiple linear regression.