Which of the following sets of compounds represents isostructural characteristics?
SF₄, CH₄, NH₃ or NF₃, BCl₃, NH₃ or BF₃, NF₃, ACl₃ or BF₃, BCl₃, BBr₃

a. SF₄, CH₄, NH₃
b. NF₃, BCl₃, NH₃
c. BF₃, NF₃, ACl₃
d. BF₃, BCl₃, BBr₃