What must a firm hold to engage in the business of planning or certifying fire extinguisher systems?

To engage in the business of planning or certifying fire extinguisher systems, a firm must hold a registration certificate. This requirement is in place to ensure that companies involved in these specialized services meet certain standards of skill, knowledge, and reliability in handling fire safety equipment. The registration certificate typically signifies that the firm has undergone the appropriate assessment or training recognized by regulatory bodies, ensuring that they adhere to safety regulations and standards in fire prevention and equipment installation.

Other options such as state approval, industry certification, or a business license may play roles in the broader context of operating a business or being recognized as a qualified service provider. However, the specific requirement for planning or certifying fire extinguisher systems directly points to the necessity of holding a registration certificate that validates a firm's compliance with specific criteria and legal standards in the fire safety industry.