The correct answer is: B. level line is normal to plumb line while horizontal line may not be normal to plumb line at the tangent point to level line.
A level line is a line that is perpendicular to the direction of gravity. A horizontal line is a line that is parallel to the surface of the Earth. In most cases, a level line will also be a horizontal line. However, this is not always the case. For example, if you are standing on a hill, the level line through your feet will be pointing down the hill, while the horizontal line will be parallel to the ground.
The plumb line is a line that points directly down, towards the center of the Earth. The tangent point to a level line is the point where the level line touches a surface.
If the level line is also a horizontal line, then the tangent point to the level line will be perpendicular to the plumb line. However, if the level line is not a horizontal line, then the tangent point to the level line may not be perpendicular to the plumb line.
For example, if you are standing on a hill, the level line through your feet will be pointing down the hill, while the plumb line will be pointing straight down. The tangent point to the level line through your feet will be at an angle to the plumb line.