The input voltage VDC of the buck-boost converter shown below varies from 32 V to 72 V. Assume that all components are ideal, inductor current is continuous, and output voltage is ripple free. The range of duty ratio D of the converter for which the magnitude of the steady-state output voltage remains constant at 48 V is

• A. \(\frac{2}{5} \le D \le \frac{3}{5}\)
• B. \(\frac{2}{3} \le D \le \frac{3}{4}\)
• C. 0 ≤ D ≤ 1
• D. \(\frac{1}{3} \le D \le \frac{2}{3}\)