**Core Concept**
Prolonged exposure to high levels of noise can cause permanent damage to the hair cells in the inner ear, leading to noise-induced hearing loss (NIHL). The severity of NIHL depends on the intensity and duration of the noise exposure.

**Why the Correct Answer is Right**
Noise levels above 160 dB can cause instantaneous damage to the hair cells in the inner ear, resulting in permanent loss of hearing. This is because such high levels of noise exceed the threshold for mechanical damage to the hair cells, which can no longer recover. In contrast, lower noise levels like 85 dB and 90 dB can cause NIHL only after prolonged exposure, typically exceeding 8 hours.

**Why Each Wrong Option is Incorrect**
**Option A:** 85 dB is the threshold for hearing damage after prolonged exposure (8 hours or more) but does not cause immediate harm.
**Option B:** 90 dB is also within the safe limits for short-term exposure (up to 8 hours) but can cause NIHL with prolonged exposure.
**Option C:** 100 dB is within the range of safe limits for short-term exposure (up to 15 minutes) and is unlikely to cause permanent hearing loss.

**Clinical Pearl / High-Yield Fact**
The National Institute for Occupational Safety and Health (NIOSH) recommends that workers be exposed to noise levels of 85 dB or less, averaged over an 8-hour shift, to prevent NIHL.