[单选题]
A +3.0-C charge is at the origins1j kdetx ah2nt/ ,39w and a +9.0-C charge is at x = 4.0 m. Where oopb l7+dql :l-n the x-axis can a third chap+:q l7- blodlrge be placed so the net force on it is zero?
A. x = 0.50 m
B. x = 0.60 m
C. x = 1.5 m
D. x = 2.4 m