Final answer:
The function f(x) represents a horizontal line, and its sign will be consistent within the interval [0,20]. The true statement can only be determined if the position of the horizontal line relative to the x-axis is specified enough to indicate whether f(x) is positive or negative over its domain.
Step-by-step explanation:
From the provided information, we can conclude that the function f(x) represents a horizontal line on the graph. Since the value of this function does not depend on x, the function will have a constant value for all x in the interval [0,20]. This implies that if f(x) is above the x-axis, then f(x) > 0 for its entire domain, and if it is below the x-axis, then f(x) < 0.
Of the given statements, none directly reference a graph, but we can infer from the description that if f(x) is a horizontal line at a positive value, it will remain positive for all x in its domain. Conversely, if it is at a negative value, it will remain negative. Without additional information specifying whether this horizontal line is above or below the x-axis, we cannot determine which of the provided statements (A-D) is true.