[单选题]
The graph shows the variation of the i 0v7u9bku kaf2g3ku2 po(zc, total ele a w2zlh-;hl1g)ocl j*rwi1c7 ctric potential due to two point electg l)i1zc w loa1whrjl7*c-; 2hric 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 $\frac{q_1}{q_2}$
