Final answer:
A pyrophoric hazard identified by Frank and his team is a fire hazard, which represents substances that can ignite spontaneously in the air and is considered a physical hazard.
Step-by-step explanation:
Frank and his team identified a pyrophoric hazard during hazard determination. The correct answer to what type of hazard they identified is D. fire hazard. Pyrophoric materials are substances that ignite spontaneously upon exposure to air at or below 54°C (129.2°F). As such, they represent a significant fire risk, which is a category of a physical hazard according to hazard classification systems like the NFPA 704 Hazard Identification System. Physical hazards involve materials that due to their properties can cause damage or harm, such as through fire or explosion.