Final answer:
Alcohol, which greatly impairs driving abilities, is present in a substantial number of fatal car crashes. The estimate closest to provided data is that it is present in nearly 40% of all fatal car crashes. Accurate statistics should be obtained from reliable and current sources.
Step-by-step explanation:
Alcohol significantly impairs decision-making and control processes, which is why it is a major contributing factor in vehicle accidents. Based on information like the estimated 50 percent of road accidents in Australia being related to alcohol overconsumption and the fact that alcohol intoxication directly results in a considerable number of deaths, it is reasonable to conclude that alcohol is present in a substantial proportion of all fatal car crashes. While the exact percentage may vary by country and over time, a plausible estimate within the provided options could be 40%, considering the severity of alcohol's impairment effects on driving abilities. However, for the most accurate and current statistics, referring to recent data from trustworthy sources such as national traffic safety authorities or health organizations is recommended.