Answer:
The most likely cause of the hearing change is a long exposure to high-frequency noise during a 4-hour flight.
Explanation:
The most common high-frequency sensorineural hearing loss is normally caused by noise exposure or aging, and often both. In this condition loud noises like a plane taking off or explosion damage the hair cells at the base of the cochlea.
The man experiencing tinnitus and hearing loss after the four-hour flight and as per the audiogram demonstration, the cause of the hearing change is most likely due to the exposure of the high-frequency sound or noise.
Thus, the correct answer is a long exposure to high-frequency noise during a 4-hour flight.