Final answer:
The range of the function f(x) = 21 for 0 ≤ x ≤ 20 is simply the value that y takes, which is 21. Therefore, the correct answer is A) y = 21.
Step-by-step explanation:
To determine the range of the graph of a given function, one needs to consider the possible y values that the function can take. Given the equation f(x) = 21 for 0 ≤ x ≤ 20, we see that this is a horizontal line, which means no matter what x value you choose (as long as it's between 0 and 20), the y value will always be 21. Therefore, the range of this function is simply all the y values that the function can assume, which in this case is just the single value 21.
So the correct answer to the question, 'What is the range of the graph?' is A) y = 21, as it is the only value y takes for the domain specified (from 0 to 20).