Rank in order, from most positive to most negative, the potential energies ua to uf of the six electric dipoles in the uniform electric field of:
a) uf, ue, ud, uc, ub, ua
b) ua, ub, uc, ud, ue, uf
c) uf, ud, uc, ub, ue, ua
d) ue, ua, ub, uc, ud, uf