The inclination of every line parallel to the x-axis is:

1. 0°

2. 90°

3. 180°

4. none of these

The inclination of y-axis is:

1. 0°

2. 45°

3. 90°

4. 180°

The slope of a horizontal line is:

1. 0

2. 1

3. 2

4. not defined

The slope of a vertical line is:

1. 0

2. 1

3. 90

4. not defined