An object's angle of elevation is the angle formed by the line of sight with the horizontal when it is viewed.

The angle of elevation is formed by the intersection of the horizontal line and the line of sight.

If the line of sight is directed upward from the horizontal line, the resulting angle is an angle of elevation

In the figure,$AB$is a vertical object with $A$ as foot and $B$ as top.

$P$ is the point of observation.

So, $\mathrm{PA}$ is the line of horizontal sight and we have to raise our head if we look at B.

The angle, described in this case $=\angle \mathrm{PAB}$ when $\mathrm{PB}$ is the line of sight.

But by definition, $\angle \mathrm{APB}$ is the angle of elevation.

Hence, option 1 is correct.