In a middle-school mentoring program, a number of the sixth graders are paired with a ninth-grade student as a buddy. No ninth grader is assigned more than one sixth-grade buddy. If \dfrac{1}{3} of all the ninth graders are paired with \dfrac{2}{5} of all the sixth graders, what fraction of the total number of sixth and ninth graders have a buddy?
Answer Choices
A. \dfrac{2}{15}
B. \dfrac{4}{11}
C. \dfrac{11}{30}
D. \dfrac{3}{8}
E. \dfrac{11}{15}