Answer:   D. [0, 5]
Step-by-step explanation:
Domain is all the x-values.  It is given that x is seconds (time).  
We know that time cannot be negative, so the lowest value x can be is 0, which represents the second it is about to be thrown.  So, the minimum value of x is 0 (inclusive).
The ball hits the ground at 5 seconds.  So it is no longer in the air after 5 seconds.  The maximum x-value is 5 (inclusive).
Time can be measured in seconds, milliseconds, or any part of a second so there are no restrictions that require the x-values to be whole numbers.
Minimum of 0 (inclusive) and maximum of 5 (inclusive) is: [0, 5]