Mathematics for IGCSE & O level - Pythagoras' Theorem And Trigonometry (Section 2 - No. 38)

Which is the following is a correct expression for the angle of elevation?

The angle between a horizontal line and a line of sight below the horizontal.

The angle between a horizontal line and a line of sight above the horizontal.

The angle between a vertical line and a line of sight below the horizontal.

The angle between a vertical line and a line of sight above the horizontal.

The angle of elevation is the angle above a horizontal line.