A
1) In this picture, we can see clearly a triangle with an adjacent leg to an angle of 50º and an opposite leg (that tree).
2) So the trigonometric ratio to be used is the one that relates both legs:
[tex]\begin{gathered} \tan (50)=\frac{opposite\text{ leg}}{\text{adjacent}} \\ \tan (50)\text{ =}\frac{x}{80} \end{gathered}[/tex]
3) Hence, the answer is A
