Final answer:
The correct function representing a horizontal line on the graph for 0≤x≤20 is C. f(x) = 10, which is the only constant function listed among the given options.
Step-by-step explanation:
The question asks to identify the function representing a graph. To determine this, we must visualize or use the description of the graph alongside the given functions. If the graph is a horizontal line, it suggests a constant function, where the value of f(x) does not change regardless of the value of x. Given the options, the only constant function is C. f(x) = 10, which is a horizontal line at the y-value of 10 for all x within the domain 0≤x≤20. Options A, B, and D represent either a constant function not equaling 10 or non-constant, linear functions with a slope. If the information were to label the graph with f(x) = 20 for 0≤x≤20, the function would be a horizontal line at the y-value of 20, which is not among the given options.
For a linear function, such as B, to be the correct choice, the graph should show a line with a slope, which would not be horizontal. Graph D would also have a slope, as it is a linear equation with a y-intercept of -4, unlike the horizontal line that the question suggests. Based on the details given, the correct function is C. f(x) = 10 as it represents a horizontal line.