**Core Concept**
Hyperkalemia with bradycardia is a life-threatening condition that requires immediate treatment to stabilize cardiac membranes and prevent cardiac arrest. The underlying principle is that hyperkalemia disrupts normal cardiac function, leading to arrhythmias and bradycardia, which can be life-threatening.

**Why the Correct Answer is Right**
Calcium gluconate is administered to stabilize cardiac membranes by antagonizing the effects of potassium on the cardiac cell membrane. It works by binding to the calcium channels and preventing potassium from entering the cells. This action helps to restore the normal functioning of the cardiac cells, thereby preventing further cardiac complications. The rapid administration of calcium gluconate is crucial in this scenario as it helps to stabilize the cardiac membranes and prevent cardiac arrest.

**Why Each Wrong Option is Incorrect**
**Option B:** Steroids are not indicated in the treatment of hyperkalemia with bradycardia. Steroids do not have a direct effect on potassium levels or cardiac function in this context.

**Option C:** Salbutamol, also known as albuterol, is a beta-2 agonist that can help to shift potassium into cells, but it is not the first-line treatment for hyperkalemia with bradycardia. Its use is more relevant in the treatment of acute asthma or COPD exacerbation.

**Option D:** Potassium resins such as polystyrene sulfonate are used to promote potassium excretion in the stool and are not indicated in the treatment of hyperkalemia with bradycardia. Their use is more relevant in the long-term management of hyperkalemia.

**Clinical Pearl / High-Yield Fact**
In cases of hyperkalemia with bradycardia, the administration of calcium gluconate should be followed by the administration of insulin and glucose to shift potassium into cells, and then by the use of potassium-binding resins to promote potassium excretion.

**✓ Correct Answer: A. Calcium gluconate**