From a data appropriateness and bias perspective, which of the following should be of GREATEST...

Using postal codes as a primary factor in credit scoring raises concerns of geographic and socioeconomic bias. Postal codes can serve as proxies for race, ethnicity, or income level—potentially violating fair lending laws and ethical guidelines.

“Auditors should flag models that rely on proxies for protected attributes. Postal codes are high-risk features that may inadvertently lead to redlining or other discriminatory practices.”

A, B, and C are more justifiable under fair lending guidelines. Thus, D presents the highest concern.