Correct answer choice is :
<h2>A) Opening, deep</h2><h2 /><h3>Explanation:</h3><h3 />
Employers shall implement and establish all fall security systems needed by this subpart for an employee, and shall comply with all other relevant demands of this subpart before that employee starts the work that requires the fallen security. When guardrail systems are used around holes used for the way of materials, the hole shall have not more than two sides rendered with movable guardrail sections to enable the way of materials.
