According to the sample exam for CQI (Certified Quality Inspector) the answer is
discrimination.
No but parallel lines have a constant distance between them
parallel lines - they are parallel when the distance between them remains constant
If the distance between the lines is constant then they are parallel.
Yes, any vertex is formed by two adjacent lines.
The distance between high voltage lines is governed by either a switching impulse voltage or lightning impulse voltage. The distance between lines, or lines and tower must have a high enough dielectric strength to avoid flashover at these voltage. Air can withstand a voltage of 3kv/mm.
Discrimination
Contour numbers.
No but parallel lines have a constant distance between them
It means when two lines meet. Parallel lines never meet; they stay exactly the same distance apart.
The elevation difference between two adjacent lines.
the elevation difference between two adjacent contour lines.
Adjacent lines are any two lines that meet at a common vertex.
contour lines
At latitude 7.25° north, 1 minute of longitude spans 1.837 km.
Color
the elevation difference between two adjacent contour lines.
parallel lines - they are parallel when the distance between them remains constant