Which of the following areas requires that employees be trained by a competent person?

Training by a competent person is essential in various areas to ensure a safe working environment, particularly in construction where risks are heightened. The practice of requiring training by a competent individual is rooted in safety regulations aimed at preventing accidents and injuries.

Scaffold safety training is necessary because employees need to understand the proper use and assembly of scaffolds, which are often involved in tasks at height. This knowledge prevents collapses and fall incidents.

Fall protection training is equally critical, as it equips employees with the skills to use safety equipment effectively, recognize potential fall hazards, and implement measures to prevent falls from heights.

Moreover, hazard communication training ensures that all employees can identify hazardous substances and understand their risks. This training is vital for maintaining safety in environments where chemicals or other hazardous materials are present.

Since each of these areas is fundamental to workplace safety in construction and mandates that training be conducted by a knowledgeable person, the choice indicating that all of the options require such training is the correct one.