Final answer:
The client's symptoms of edema, lung crackles, and frothy cough are indicative of congestive heart failure, which leads to fluid accumulation in the lungs and extremities.
Step-by-step explanation:
The client described is suffering from symptoms that include edema of the feet and ankles, crackles in the lower lobes of the lungs, and a frothy productive cough. These findings are suggestive of congestive heart failure (CHF). In CHF, the heart's diminished capacity to pump blood leads to an accumulation of fluid in the lungs (pulmonary edema) and the extremities due to increased hydrostatic pressure in the capillaries. This can result in the observed edema and lung congestion, which causes crackling sounds during respiration and may lead to a frothy cough. Therefore, the correct answer to the question is a) Congestive heart failure.