Given an enzyme with a kcat of 500 s^-1 and a Km of 0.05 M, calculate the specificity constant and explain its significance.

• A. 5,000 M^-1 s^-1; indicates moderate efficiency at high substrate concentrations.
• B. 25,000 M^-1 s^-1; indicates low efficiency at low substrate concentrations.
• C. 1,000 M^-1 s^-1; indicates low efficiency at high substrate concentrations.
• D. 10,000 M^-1 s^-1; indicates high efficiency at low substrate concentrations.

Answer: (D)