Final answer:
The function f(x) is described as a horizontal line restricted to the interval between x = 0 and x = 20, inclusive. The correct option is (-0, 0) as there is no interval in which the function is positive.
Step-by-step explanation:
The function f(x) is described as a horizontal line that is restricted to the interval between x = 0 and x = 20, inclusive. Since the graph of a horizontal line is constant, the entire interval over which the function is positive depends on whether the horizontal line is above or below the x-axis.
If the line is above the x-axis, the entire interval would be (0, 20). However, if the line is below the x-axis or coincides with the x-axis, there is no interval where the function is positive.
Based on the information provided, we can determine that the correct answer is option C) (-0, 0) as there is no interval in which the function is positive.