Consider the species \( \mathrm{CH_4} \), \( \mathrm{NH_4^+} \) and \( \mathrm{BH_4^-} \). Choose the correct option with respect to the there species.
They are isoelectronic and only two have tetrahedral structures
They are isoelectronic and all have tetrahedral structures
Only two are isoelectronic and all have tetrahedral structures
Only two are isoelectronic and only two have tetrahedral structures