A correlation of .20 is found between education and income in a representative sample of residents in city X. However, the correlation is not statistically significant.
On the basis of this outcome alone, which of the following conclusions is most warranted?

a. Increased education generally results in no increase in income in most cities. Because we know city X has a composition typical of most cities, the finding can be easily generalized to most cities.
b. In city X, people with advanced degrees are wealthy. That is, we know that in city X, getting an advanced degree leads to having an income in the upper-middle-class range or higher.
c. No significant relationship between education and income was established.