Option 1 -> AFC is not constant; it changes with output levels.
Option 2 -> U-shaped curve is characteristic of ATC and AVC, not AFC.
Option 3 -> AFC = TFC/Q, creating a rectangular hyperbola that continuously falls as output increases.
Option 4 -> This is not a standard economic curve shape.
Hence, Option 3: Rectangular Hyperbola -> The Average Fixed Cost (AFC) curve is a rectangular hyperbola because AFC = Total Fixed Cost / Quantity. Since Total Fixed Cost remains constant at all output levels, as quantity (Q) increases, AFC continuously decreases. The curve approaches both axes asymptotically - it gets closer to the X-axis as output increases (but never touches zero) and approaches infinity as output approaches zero. This mathematical relationship (constant divided by variable) creates the distinctive rectangular hyperbola shape where AFC × Q = constant (TFC). -> correct