Which of the following cannot be used as dehydrating agents for ammonia?

Being a basic gas, ammonia will not get dehydrated by conc.${\mathrm{H}}_2{\mathrm{SO}}_4,\text{ anhydrous }{\mathrm{CaCl}}_2\text{ and }{\mathrm{P}}_4{\mathrm{O}}_{10}$ whereas it can directly react with them.
$\begin{array}{l}{\mathrm{H}}_2{\mathrm{SO}}_4+2{\mathrm{NH}}_3⟶{\left({\mathrm{NH}}_4\right)}_2{\mathrm{SO}}_4\\ {\mathrm{CaCl}}_2+8{\mathrm{NH}}_3⟶{\mathrm{CaCl}}_2\cdot 8{\mathrm{NH}}_3\\ {\mathrm{P}}_4{\mathrm{O}}_{10}+12{\mathrm{NH}}_3+6{\mathrm{H}}_2\mathrm{O}⟶4{\left({\mathrm{NH}}_4\right)}_3{\mathrm{PO}}_4\end{array}$