Which of the following species can exist?

Boron cannot have a covalency greater than four…(1) and (4) cannot exist;

Initially formed two Pb-I bonds are not sufficiently energetic to excite the electrons of Pb…..${\mathrm{PbI}}_4$ cannot exist ;

Maximum covalency of Al is six. $\therefore {\left[{\mathrm{AlF}}_6\right]}^{-3}$can exist ;