[单选题]
The gravitational attractive force between tu6e+kwx: ;c7s0ejceg u r63: k frk)hewo masses is F. If the masses are s ybq,8 uazy7.(:kpoo)+ d khdmoved to half of their initial distance, what is the gravitational ,ysk)y+k:d. u7qo pa8(bhoz dattractive force?
