[单选题]
A copper penny has a mass oj,jw 82h ,gm a8-xlub;vc t6wsf 3.0 g. A total sa.:nlz2s2y hnso/*ued av 6u+a8o 2l of are transferred from one neutral penny to another. If the electrostatic force of attraction between the pennies is equal to the weight of a penny, what is the separation between them?