**Core Concept**
Tetralogy of Fallot is a congenital heart defect characterized by four key features: ventricular septal defect, pulmonary stenosis, right ventricular hypertrophy, and an overriding aorta. The primary goal in managing Tetralogy of Fallot is to increase pulmonary blood flow and alleviate cyanosis.

**Why the Correct Answer is Right**
Calcium channel blockers are not used in the treatment of Tetralogy of Fallot because they can further decrease the already compromised pulmonary blood flow, exacerbating cyanosis. This is due to their vasodilatory effect on peripheral arteries, which can lead to a decrease in systemic vascular resistance. In contrast, the other options are used to manage the condition by increasing pulmonary blood flow or alleviating symptoms.

**Why Each Wrong Option is Incorrect**
**Option A:** β blockers are used in the treatment of Tetralogy of Fallot to control the symptoms of cyanosis by reducing the frequency and severity of episodes of intense cyanosis, known as "tet spells." They work by decreasing the heart rate and reducing the contractility of the heart, which in turn decreases the right-to-left shunt.

**Option B:** α agonists, such as phenylephrine, can be used in the treatment of Tetralogy of Fallot to increase systemic vascular resistance, which can help alleviate cyanosis by increasing the right-to-left shunt.

**Option D:** Morphine is used in the treatment of Tetralogy of Fallot to alleviate pain and anxiety during episodes of intense cyanosis. It can also help reduce the frequency and severity of these episodes.

**Clinical Pearl / High-Yield Fact**
It's essential to note that the management of Tetralogy of Fallot involves a multidisciplinary approach, including surgical intervention, and medical management with β blockers, α agonists, and morphine.

**✓ Correct Answer: C. Calcium channel blockers**