A 69-year-old patient has worsening respiratory symptoms secondary to congestive heart failure.

The correct answers are A, B, and C . Proper lung auscultation technique includes listening to at least one full respiratory cycle at each location and placing the stethoscope on bare skin rather than over clothing. Authoritative respiratory examination guidance also emphasizes comparing both sides systematically. ( PMC )

For a patient with congestive heart failure , it is appropriate to auscultate the bilateral lung bases first because CHF commonly produces bilateral basal crackles from pulmonary edema, often most noticeable at the posterior bases. ( NCBI )