Answer: Option (d) is the correct answer.
Step-by-step explanation:
Bases are the electron rich species which readily accept a proton. Therefore, when ammonia is classified as a base in a chemical reaction with an acid, it readily accepts a proton to give ammonium cation.
For example, the reaction of ammonia with hydrochloric acid will be as follows.

Thus, we can conclude that ammonia,
, will accept a proton and become
.