Answer :
EXPLANATION:
-The points of the independent variable that represent the domain of a function on a graph are always located on the x axis.
-The domain of a function is the range of values of x for which f (x) exists, that is, the values of x, for which f (x) has a result.
In the graph corresponds to the independent variable of time that corresponds to the real numbers on the positive axis between 0 and 40
NOTE:
"The domain is the range of values of x, for which the function is drawn above. As we can see, from 0 to 40, the function is drawn. At no other value of x more"