Which information must financial institutions request from loan applicants for a principal dwelling?

The requirement for financial institutions to collect certain demographic information from loan applicants is tied to the regulations established under applicable fair lending laws, specifically the Home Mortgage Disclosure Act (HMDA). The intent behind collecting this data is to ensure compliance, prevent discrimination, and promote fair lending practices.

The correct choice encompasses ethnicity, race, sex, marital status, and age, all of which are critical parameters that financial institutions are mandated to gather. This information is important because it contributes to the analysis of lending patterns and helps regulators assess whether there may be discrimination occurring in lending practices based on these characteristics.

The inclusion of marital status is particularly relevant as it assists in understanding the applicant's financial responsibilities and stability, influencing lending decisions. Furthermore, this comprehensive set of demographics allows for a more thorough overview of the borrowers, helping to foster transparency and accountability in the lending process.

In contrast, the other answer choices miss some of these essential components required for full compliance with HMDA and other fair lending requirements. They either lack critical identifiers such as marital status or do not provide a complete picture of the applicant demographics as specified by regulations. Collectively, these aspects ensure that financial institutions are also able to address the needs of a diverse clientele effectively.