Which of the following drug acts as a stimulant of CNS?

Options

A. Heroin
B. Morphine
C. Cocaine
D. Marijuana

Answer

To determine which drug acts as a stimulant of the central nervous system (CNS), we can analyze the options provided:

1. **Heroin**: This drug is an opioid and primarily acts as a depressant rather than a stimulant. It can create feelings of euphoria but does not stimulate the CNS.

2. **Morphine**: Similar to heroin, morphine is also an opioid and functions as a depressant. It is used for pain relief and does not stimulate the CNS.

3. **Cocaine**: This drug is known to be a powerful stimulant of the CNS. It increases alertness, energy, and can elevate mood. Cocaine affects various neurotransmitters in the brain, leading to its stimulating effects.

4. **Marijuana**: While marijuana can have various effects on the body, it is not primarily classified as a CNS stimulant. It can have depressant and hallucinogenic effects depending on the strain and dosage.

Based on this analysis, the drug that acts as a stimulant of the CNS is **Cocaine**.

### Step-by-Step Solution:
1. **Identify the drugs listed in the question**: Heroin, Morphine, Cocaine, and Marijuana.
2. **Analyze the effects of each drug on the CNS**:
- **Heroin**: Acts as a depressant.
- **Morphine**: Acts as a depressant.
- **Cocaine**: Acts as a stimulant.
- **Marijuana**: Not primarily a stimulant.
3. **Determine which drug stimulates the CNS**: Cocaine is the only drug in the list that acts as a stimulant.
4. **Conclude the answer**: The correct answer is Cocaine.