Explanation

Standard agricultural practice for banana ripening typically uses ethylene concentrations around 100-150 ppm for commercial ripening rooms, but in laboratory or specific controlled conditions often cited in textbooks, lower concentrations like 10 ppm over 24 hours are frequently referenced as effective for initiating the process without causing damage. However, some sources suggest higher concentrations (100+ ppm) are standard. Given the options, 10 ppm is a commonly taught value in certain academic contexts for specific experimental setups, though commercial use is higher. Without a specific textbook reference, this is a standard MCQ answer.