Which organization provides a 24-hour information service for chemical emergencies?

CHEMTREC (Chemical Transportation Emergency Center) is the correct choice because it serves as a 24-hour emergency response service specifically for chemical-related incidents. This agency provides immediate assistance to first responders, businesses, and the public during chemical emergencies, ensuring that accurate information and guidance is readily available to handle dangerous situations effectively. CHEMTREC's assistance is critical in situations involving hazardous materials, as they can provide information on how to safely manage spills, leaks, and exposures.

While the other organizations listed offer valuable resources and services related to chemical safety and regulation, they do not specifically focus on providing a dedicated 24-hour emergency response service for chemical incidents. For instance, the Environmental Protection Agency deals largely with environmental regulatory oversight and compliance, and the Occupational Safety and Health Administration focuses on workplace safety regulations rather than direct emergency response. The Chemical Safety Board investigates chemical accidents but does not provide immediate emergency response services.