How long did it take Dahl to go solo according to his log book?

The correct answer reflects the specific duration that Dahl noted in his logbook, indicating that it took him 7 hours and 40 minutes to go solo. This detail is significant as it showcases the careful documentation of his flight training progress. The time spent is not only a measure of his skills developing as a pilot but also highlights the rigorous nature of flight training during that period. Each flight training session and the milestones achieved are crucial for understanding the learning curve that pilots undergo, particularly for someone like Dahl, who transitioned from a military background to becoming a civilian pilot. The other choices represent different lengths of time, but only the 7 hours and 40 minutes accurately matches Dahl’s recorded achievement in his logbook, emphasizing the importance of that specific detail in the context of his aviation experience.