In the diagram, each of p, q, r, s, t, u, v is to be replaced with 1,2 or 3 so that p, q and r are all different, q, s and t are all different, and r, u and v are all different. What is the maximum possible value of s+t+u+v ?
Answer Choices
A. 8
B. 9
C. 11
D. 7
E. 10