What assessment finding would indicate the patient's left-sided heart failure is worsening?

The correct answer is D: Increased crackles in lung fields. Worsening left-sided heart failure causes fluid to accumulate in the lungs, leading to crackles on auscultation. Increased jugular venous pressure (A) is more indicative of right-sided heart failure. Liver enlargement (B) is a sign of congestive hepatomegaly, common in right-sided heart failure. Increased pulse rate (C) may indicate heart failure exacerbation but is not specific to left-sided failure. Therefore, choice D is the best indicator of worsening left-sided heart failure.