AMC 12B 2005 Problem 12

The quadratic equation x^{2}+m x+n=0 has roots that are twice those of x^{2}+p x+m=0, and none of m, n and p is zero. What is the value of n / p ?

Answer Choices
A. 1
B. 2
C. 4
D. 8
E. 16