Write an equation for the reaction of HCl with NH₃, a strong protic acid, and show by the use of curved arrows how the reaction occurs.

a) NH₃ + HCl → NH₄Cl
b) NH₄Cl → NH₃ + HCl
c) NH₃ + HCl → NH₃Cl + H
d) HCl + NH₃ → NH₄Cl