Suppose a correlation is found between intelligence and the size of the frontal lobe of the brain. Which of the following statements would be most accurate?

    a.    A large frontal lobe causes a person to be intelligent.
    b.    Being intelligent causes a person to have large frontal lobes.
    *c.    As frontal lobe size increases, so does intelligence.
    d.    Intelligence and frontal lobe size are unrelated.