Final answer:
Digoxin is the medication that should NOT be given to newly diagnosed patients with heart failure with reduced ejection fraction (HFrEF) who are in acute failure.
Step-by-step explanation:
The medication that should NOT be given to newly diagnosed patients with heart failure with reduced ejection fraction (HFrEF) who are in acute failure is Digoxin (A). Digoxin is a cardiac glycoside that strengthens the heart's contractions and slows down the heart rate, which can be beneficial in stable heart failure patients. However, in acute heart failure, Digoxin may exacerbate symptoms and even increase the risk of arrhythmias. Therefore, it is contraindicated in newly diagnosed patients with HFrEF in acute failure.