On a job site where workers are exposed to high noise levels for extended periods, the employer should:

Explanation

Where noise exposure exceeds the permissible limit, feasible administrative or engineering controls must be used first, and where they do not bring exposure within the limit the employer must provide hearing protectors and run a hearing conservation programme: monitoring, audiometric testing, a choice of protectors, training and recordkeeping. Option (a) is an administrative control and genuinely comes first in the order; what makes it wrong as the whole answer is that rotation shares the dose without removing the duty to run the programme once the action level is reached. Option (c) issues protectors and drops everything else, including the audiometric testing that reveals whether they are working. Option (d) substitutes a sign for a control, and noise damage is cumulative and painless - a warning changes nothing about the exposure.