Answer:
They limit the choices available
Explanation:
Take an example of UNIQUE constraint. It limits the output to have UNIQUE values. All duplicate values are being cleaned. And only the unique values are shown in the search list. Hence, this means that the constraint limits the choices available. No modification of the value is done by it. Nor does it evaluate the outcomes. Also, it does not add more choices as well as options. But it does limit the choices available. Hence, the correct option is certainly C. or that it limits the choices available.
