What does the horizon line show?

a: where the background and foreground meet

b: where the ground and sky meet

c: where the ground and bottom of the paper meet

d: where the sky and top of the paper meet

how many vanishing points are used in one-point perspective?
a: 0

b: 1

c: 2

d: 3

4. where do orthogonal lines meet?

a: anywhere on the horizon line

b: on other orthogonal lines

c: at the top of the paper

d: at the vanishing point