A train moves towards a stationary observer with speed 34 m/s. The train sounds a whistle and its frequency registered by the observer is f1. If the speed of the train is reduced to 17 m/s, the frequency registered is f2. If speed of sound is 340 m/s, then the ratio \(\frac{{{f_1}}}{{{f_2}}}\) is

• A. \(\frac{{19}}{{18}}\)
• B. \(\frac{{21}}{{20}}\)
• C. \(\frac{{20}}{{19}}\)
• D. \(\frac{{18}}{{17}}\)