If f: A → B is a one-one function, it is called a:

Surjective function

Constant function

Injective function

Bijective function

A one-one function means that each element of the domain maps to a unique component of the codomain.

This is the definition of an injective function.

A bijective function is both injective and surjective.

A surjective function covers every element in the codomain.

A constant function maps all domain elements to the same codomain value — it is not injective.