Answer: Option (d) is the correct answer.
Step-by-step explanation:
An acid which gives only one hydrogen ion or
ions upon dissociation in an aqueous solution is known as a monoprotic acid.
Whereas when an acid gives two hydrogen or
ions upon dissociation in an aqueous solution is known as a diprotoc acid.
And when an acid gives three hydrogen or
ions upon dissociation in an aqueous solution is known as a triprotoc acid.
Therefore dissociation of the given acids in an aqueous solution will be as follows.




Hence, we can conclude that out of the given options, HCl is the monoprotic acid.