Ammonia Gas Dissolves in Water and Can React According to the Equation

Ammonia gas dissolves in water and can react according to the equation NH₃ + H₂O NH₄⁺ OH^-.The amount of ammonium ion in solution will be increased by which one or more of the following?

A) Increase the pressure of NH₃ above the solution.
B) Pump off the gas above the solution.
C) Raise the temperature of the solution.
D) Add HCl to the solution.
E) Both A and D