Which of the following classifications prohibits insurers from refusing coverage based on certain criteria?

The correct classification that prohibits insurers from refusing coverage based on certain criteria is race. This stems from federal and state laws that protect individuals from discrimination in various areas, including insurance. The Federal Civil Rights Act, along with various state regulations, emphasizes that insurance companies cannot deny coverage based on race, ensuring that all individuals have equal access to insurance products regardless of their racial background.

In the context of the other classifications, while age and marital status may also be subject to certain regulations about how insurers can use those criteria in underwriting, they do not have the same blanket prohibition as race. Occupational hazards, while a factor in assessing risk and determining coverage, are specific to job roles and do not involve discrimination in the same sense as race does. Understanding these distinctions is key in the field of insurance and compliance with anti-discrimination laws.