Final answer:
The most recognizable side effect of Furosemide in a child with CHF is increased urine output. This occurs because Furosemide is a loop diuretic which impedes the reabsorption of sodium and chloride ions leading to greater urine production.
Step-by-step explanation:
The sign or symptom that most clearly relates to a side effect of Furosemide in a 3-month-old child with congestive heart failure (CHF) is D) Increased urine output. Furosemide is a type of loop diuretic commonly used to treat conditions such as hypertension and CHF. Loop diuretics work by inhibiting the reabsorption of sodium (Na+) and chloride (Cl-) ions in the ascending limb of the loop of Henle in the nephron, which leads to increased urine production. The consequences of this effect may include dehydration and electrolyte imbalances, but hyperkalemia (increased potassium levels) is not typically associated with Furosemide, as it tends to cause hypokalemia (decreased potassium levels) instead.