Under the Essential Insurance Act (MCL 500.2111), which underwriting factor is expressly prohibited for personal auto rating in Michigan?

Why this is the answer

MCL 500.2111 of the Essential Insurance Act lists the permitted personal-auto classification factors and, in subsection (4), bars rates or rating classifications based on sex, marital status, home ownership, educational level, occupation, the postal zone where the insured lives, or credit score. Permitted factors include driving experience, vehicle type, mileage, and use, and every insurer must surcharge at-fault accidents and moving violations under a merit rating plan.