Among the following, basic oxide is :

Options

A. `SO_3`
B. `SiO_2`
C. `CaO`
D. `Al_2O_3`

Explanation

To determine which among the given options is a basic oxide, let's analyze the characteristics of different types of oxides.

### Step-by-Step Solution:

1. **Understanding Oxides**:
- Oxides can be classified into three main categories: acidic oxides, basic oxides, and amphoteric oxides.
- Acidic oxides are typically formed by non-metals (e.g., SO3, SiO2).
- Basic oxides are generally formed by metals (e.g., Na2O, CaO).
- Amphoteric oxides can react with both acids and bases (e.g., Al2O3, PbO).

2. **Identifying the Options**:
- We need to identify the oxides provided in the options. Let's assume the options include: SO3, SiO2, Al2O3, and possibly a metal oxide like Na2O or CaO.

3. **Classifying Each Oxide**:
- **SO3 (Sulfur Trioxide)**: This is an acidic oxide because sulfur is a non-metal.
- **SiO2 (Silicon Dioxide)**: This is also an acidic oxide as silicon is a non-metal.
- **Al2O3 (Aluminum Oxide)**: This is an amphoteric oxide because aluminum can exhibit properties of both metals and non-metals.
- **Na2O (Sodium Oxide)**: This is a basic oxide because sodium is a metal.

4. **Conclusion**:
- Among the options, the basic oxide is **Na2O** (or any other metal oxide if provided).

### Final Answer:
The basic oxide among the given options is **Na2O** (or the equivalent metal oxide).