The Km value of a certain enzyme is known to be 25 , (mmol/L). To achieve 50% of the maximum reaction velocity of the enzyme catalyzed reaction, the concentration of the substrate should beA. 12.5 , (mmol/L)B. 25 , (mmol/L)C. 37.5 , (mmol/L)D. 50 , (mmol/L)

The Km value of a certain enzyme is known to be $25 \, \text{mmol/L}$. To achieve $50\%$ of the maximum reaction velocity of the enzyme catalyzed reaction, the concentration of the substrate should be

A. $12.5 \, \text{mmol/L}$

B. $25 \, \text{mmol/L}$

C. $37.5 \, \text{mmol/L}$

D. $50 \, \text{mmol/L}$