Final answer:
The domain of the composite function f(g(x)) depends on the function g(x). Since f(x) is a horizontal line from 0 to 20, only the x-values for which g(x) falls in this range can be part of the domain for f(g(x)). Without specific information about g(x), we cannot determine the exact domain.
Step-by-step explanation:
The domain of the composite function f(g(x)) is determined by the values of x for which g(x) is defined and for which f(g(x)) is also defined. Since f(x) is defined as a horizontal line for 0 ≤ x ≤ 20, the composite function f(g(x)) will be restricted to the values of g(x) that fall within that interval. Without knowing the specific function g(x), we cannot determine a precise domain. If g(x) produces values outside of the 0 to 20 range, those x-values would not be in the domain of f(g(x)). Conversely, if g(x) <= 20 for all x in its domain, then those values would be in the domain of f(g(x)). Without additional information about g(x), we cannot choose from the provided options A) x ≠ 0, B) x > 0, C) x < 0, or D) No restrictions on x.