**Core Concept**
The acceptable noise level in industries is a critical aspect of occupational health and safety, as excessive noise exposure can lead to permanent hearing loss and other auditory disorders. The National Institute for Occupational Safety and Health (NIOSH) and the Occupational Safety and Health Administration (OSHA) have established guidelines for permissible noise levels in the workplace. Noise levels are typically measured in decibels (dB) and are categorized into different zones based on their potential impact on hearing.

**Why the Correct Answer is Right**
The correct answer is based on the guidelines established by NIOSH and OSHA, which recommend that the permissible exposure limit (PEL) for noise in industries should not exceed 90 decibels (dB) over an 8-hour time-weighted average (TWA). This is because prolonged exposure to noise levels above 90 dB can cause permanent hearing loss. The noise level is calculated using the A-weighted decibel scale, which takes into account the frequency response of the human ear.

**Why Each Wrong Option is Incorrect**
**Option A:** 80 dB is an acceptable noise level in some industries, but it is not the correct answer. While noise levels below 90 dB may be less hazardous, they can still cause hearing damage with prolonged exposure.
**Option B:** 100 dB is above the permissible exposure limit and can cause significant hearing loss even with short-term exposure.
**Option C:** 110 dB is extremely hazardous and can cause permanent hearing loss with even brief exposure.

**Clinical Pearl / High-Yield Fact**
It's essential to note that the noise level can be reduced by implementing noise-reducing measures, such as using earplugs, earmuffs, or improving ventilation systems, and to conduct regular audiometric tests to monitor noise-induced hearing loss.

**Correct Answer: D. 90 dB**