27. An enzyme that follows standard Michaelis-Menten kinetics was assayed for reaction velocity at various substrate concentrations. The data are shown below: Based on these kinetic data for the enzyme, what would be the closest estimate of the enzyme's Km value? (A) 2.0mM (B) 1.0mM (C) 250mM (D) 0.5 mM (E) 3.0mM