[单选题]
The graph shows the variation of the total w xr140kikjfn 4xj)/yelectric potenti h6cqf3vq e31xal due to two point electr3vh3e cx1qq6fic charges $q_1$ and $q_2$ located 4.0m apart. The distance r is defined to be zero at the location of $q_1$.
What is the ratio of $\frac{q_1}{q_2}$
