`X` -axis is the intersection of two planes.

Options

A. `XY` and `XZ`
B. `YZ` and `ZX`
C. `XY` and `YZ`
D. `"none of these"`

Explanation

To solve the problem of determining how the x-axis can be represented as the intersection of two planes, we can follow these steps:

### Step 1: Understand the Planes
The x-axis can be represented in three-dimensional space as the line where both y and z coordinates are zero. Therefore, we need to identify two planes that intersect along this line.

### Step 2: Define the Planes
We can define two planes in the three-dimensional coordinate system:
1. **Plane 1 (x-y Plane)**: This is defined by the equation \( z = 0 \). This plane contains all points where the z-coordinate is zero, which includes the entire x-axis.
2. **Plane 2 (y-z Plane)**: This can be defined by the equation \( x = 0 \). This plane contains all points where the x-coordinate is zero, which does not directly help us find the x-axis.

Instead, we can use a different plane:
2. **Plane 2 (z-x Plane)**: This can be defined by the equation \( y = 0 \). This plane contains all points where the y-coordinate is zero, which also includes the entire x-axis.

### Step 3: Find the Intersection
Now, we have:
- Plane 1: \( z = 0 \) (x-y plane)
- Plane 2: \( y = 0 \) (z-x plane)

To find the intersection of these two planes, we set both equations simultaneously:
1. From Plane 1: \( z = 0 \)
2. From Plane 2: \( y = 0 \)

### Step 4: Write the Intersection
The intersection of these two planes is where both conditions are satisfied:
- \( y = 0 \)
- \( z = 0 \)

This means that any point on the x-axis can be represented as \( (x, 0, 0) \), where \( x \) can take any real number value.

### Conclusion
Thus, the x-axis is indeed the intersection of the two planes defined by the equations \( z = 0 \) and \( y = 0 \).

---