Which of the following is a condition under which income does not need to be disclosed by a loan applicant?

The correct choice is that income does not need to be disclosed by a loan applicant if it is not being used to qualify for the loan. This principle is rooted in the process of determining a borrower's ability to repay the loan. Lenders are primarily concerned with reliable and relevant sources of income that will impact the loan's risk assessment.

When an applicant lists income that is not factored into the loan qualification process, it becomes unnecessary for the lender to consider or include this income in their assessment. For example, an applicant might have additional income sources that are irregular or not steady, and if these sources aren't influencing the lender's decision, there's no need to disclose them.

In contrast, non-reliable income, undocumented income, or income below a specific threshold can still be elements that require consideration depending on the lender’s policy or guidelines. However, if the income is explicitly not being utilized in the calculation of qualifying for the loan, it is effectively irrelevant to the lending decision.