An observational study shows that 8th grade students who are taking music lessons also score an average of 12 points higher on a math test than students who are not taking music lessons. What can you conclude from this study?

a. Taking music lessons is associated with better math skills, but a confounding variable may be parental income or involvement.

b. Taking music lessons causes a corresponding improvement in math skills in 8th graders.

c. Musicians are generally better at math than non-musicians because the two subjects are related.