The inverse demand function for a product is given by P = 9 - 2Q. The firms producing this product are proposing to merge into a single firm. Marginal cost is 3 per unit. The pre-merger price is 5. Suppose that the "Small but Significant and Nontransitory Increase in Price" threshold is 5%. Making use of critical elasticity of demand analysis, do the existing producers of this product represent an antitrust market, or do additional substitutes need to added to the market.