AMC 8 1989 Problem 25

Every time these two wheels are spun, two numbers are selected by the pointers. What is the probability that the sum of the two selected numbers is even? $\text{(A)}\ \frac{1}{6} \text{(B)}\ \frac{3}{7} \text{(C)}\ \frac{1}{2} \text{(D)}\ \frac{2}{3} \text{(E)}\ \frac{5}{7}$