Which of the following is a requirement for guardrails?

Guardrails are essential safety features designed to prevent falls from elevated surfaces, and their structural integrity is critical in ensuring user safety. The requirement that guardrails must withstand at least 150 lbs of force is based on safety codes and regulations that dictate how well guardrails need to perform under pressure. This force ensures that the guardrail can effectively prevent a person from falling over the edge, providing a crucial barrier in situations where there is a risk of height-related accidents.

The requirement for a specific force capacity addresses practical safety concerns, such as the potential impact from a person leaning or pushing against the guardrail, and it reflects the expectation that the guardrail should remain stable and secure. Hence, the specification of 150 lbs is part of broader guidelines to ensure safety in construction and design.

Other options like the need for easy dismantling, a decorative finish, or adjustability in height do not directly relate to the primary function of guardrails, which is to enhance safety by creating a reliable physical barrier. While these features might have their own merits in different contexts, they do not meet the fundamental safety requirement focused on force capacity that B fulfills.