Final answer:
OSHA requires that employees engaged in site clearing are protected from irritant and toxic plants and receive instruction in first aid treatment, making C) Both A and B the correct answer.
Step-by-step explanation:
The Occupational Safety and Health Administration (OSHA) has clear regulations for the protection of employees in various work environments, including those engaged in site clearing activities. The requirement specifically states that employees must be protected from the hazards of irritant and toxic plants and must be suitably instructed in the available first aid treatment. Therefore, the correct answer to what is required by OSHA for employees engaged in site clearing would be C) Both A and B: Protection from hazards of irritant and toxic plants AND Suitable instruction in the first aid treatment available.