The average fixed cost (AFC) curve is asymptote to:

Asymptote of a curve is a line such that the distance b/w the curve and the line approaches zero and the slope of the curve at the point approaches the slope of the line. So asymptote is, essentially, a line that a graph approaches, but does not intersect. The AFC curve is horizontal asymptote b/c it gets closer and closer to X-axis but never intersect it.}