Distinct points P, Q, R, and S lie on the circle x^{2}+y^{2}=25 and have integer coordinates. The distances P Q and R S are irrational numbers. What is the greatest possible value of the ratio \dfrac{P Q}{R S} ?
Answer Choices
A. 3
B. 5
C. 3 \sqrt{5}
D. 7
E. 5 \sqrt{2}