Final answer:
The factory worker in a noisy environment is most likely to experience a rapid decline in hearing.
Step-by-step explanation:
The most likely 50-year-old to experience a rapid decline in hearing would be the C. Factory worker in a noisy environment. Noise exposure is a major cause of hearing loss, and working in a noisy environment increases the risk. Frequent concertgoers and nature enthusiasts who enjoy hiking may also be exposed to loud sounds, but the level of noise exposure in a factory setting is typically higher and more constant.