Answer: Option (d) is the correct answer.
Step-by-step explanation:
According to Bronsted-Lowry an acid is defined as the specie which is able to donate hydrogen ions when dissolved in water.
For example,

On the other hand, bases are the species which are able to donate hydroxide ions when dissolved in water.
For example,

Thus, we can conclude that a definition of an acid is that it donates H ions when dissolved in water.