Final answer:
The range of a function represented by a horizontal line within the interval 0 ≤ x ≤ 20 is a single constant value, which is the y-value of the horizontal line.
Step-by-step explanation:
The question seems to be asking for the range of a certain function defined in the interval 0 ≤ x ≤ 20. Since it's mentioned that the graph of the function is a horizontal line, this indicates that the function has a constant value for any x within the given domain. Therefore, the range will also consist of a single value, which is the y-value of the horizontal line.
If we suppose the constant value is 'k', then the function will be f(x) = k for all x such that 0 ≤ x ≤ 20. The range will thus be {k}, because for every x in the domain, the function yields the same output k.
Without further information about the specific function (such as the function's expression or a value for k), we cannot precisely define the range other than to say it is a constant value.