ANS:A - 15 to 25

In practice, the compression ratio of compression-ignition (CI) engines typically ranges from 15 to 25. This range may vary depending on factors such as engine design, fuel type, and intended application. However, for most diesel engines, the compression ratio falls within this range. The compression ratio is a critical parameter in CI engines as it determines the efficiency of the combustion process and influences factors such as power output, fuel consumption, and emissions.