**Core Concept**
Salbutamol, a short-acting beta-2 agonist, is a medication used to treat bronchospasm in conditions such as asthma and COPD. Its mechanism of action involves binding to beta-2 adrenergic receptors in the lungs, leading to bronchodilation and relaxation of smooth muscle.

**Why the Correct Answer is Right**
The correct answer is related to the side effects of salbutamol, which can be attributed to its mechanism of action. Salbutamol can cause **tachycardia** due to its effects on the heart, **hypokalemia** due to potassium efflux from cells, and **muscle tremors** due to its effects on muscle receptors. Additionally, salbutamol can cause **rebound bronchospasm** or **rebound asthma** with prolonged use, as the body adapts to the constant presence of the medication.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not a known side effect of salbutamol. **Option B:** This option is a known side effect of salbutamol, as it can cause an increase in heart rate. **Option C:** This option is also a known side effect of salbutamol, as it can cause a decrease in potassium levels.

**Clinical Pearl / High-Yield Fact**
One key point to remember is that salbutamol can cause **rebound bronchospasm** with prolonged use, making it essential to use this medication judiciously and under medical supervision.

**Correct Answer: C. None of the above**