Answer:
A All real numbers
Step-by-step explanation:
You want to know the domain of a function graphed as a continuous line with negative slope.
The domain is the horizontal extent of the function, all of the values for which the function is defined.
The graph shows the function is defined not only for all integers (..., -1, 0, 1, ...), but also for all the values between.
The domain is all real numbers.