Final answer:
The lender provides an adverse action notice to inform the applicant of the denial and the reason(s) for it.
Step-by-step explanation:
When a lender denies a mortgage loan, they are required to provide the applicant with a document called an adverse action notice. This notice informs the applicant of the denial and provides the reason(s) for the denial. It is a legal requirement under the Equal Credit Opportunity Act (ECOA) and the Fair Credit Reporting Act (FCRA) to provide the adverse action notice.