The correct statement(s) about compounds of the p-block elements is/are

A: In $\mathrm{NCl_3}$ the oxygen of water attacks the chlorine atoms (which carry the partial positive character in this hydrolysis), while the nitrogen, using its lone pair, is protonated; nitrogen therefore ends up as $\mathrm{NH_3}$ and chlorine as HOCl: $\mathrm{NCl_3+3H_2O\to NH_3+3HOCl}$. Correct. B: Solid $\mathrm{PCl_5}$ is ionic, $[\mathrm{PCl_4}]^+[\mathrm{PCl_6}]^-$ with tetrahedral cation and octahedral anion; the charges in the statement are reversed, so B is wrong. C: The Lewis acidity of boron halides increases $\mathrm{BF_3<BCl_3<BBr_3}$, because the $2p\pi$-$2p\pi$ back-donation from F into the empty boron $2p$ orbital is strongest in $\mathrm{BF_3}$ and reduces its acidity; C is wrong. D: The electronegative fluorines in $\mathrm{NF_3}$ pull electron density away from the lone pair and the dipoles oppose it, so $\mathrm{NF_3}$ is a much weaker Lewis base than $\mathrm{NH_3}$; D is wrong. Answer: A only.