Answer: Second option.
Step-by-step explanation:
As you can observe in the picture given in the exercise, there are two Right triangles formed inside the rectangle: CDA and ABC.
You need to use the Pythagorean Theorem to solve this exercise. This is:
[tex]a^2=b^2+c^2[/tex]
Where "a" is the hypotenuse and "b" and "c" are the legs of the Right triangle.
If you solve for one of the legs, you get the following equation:
[tex]a^2-c^2=b^2\\\\b=\sqrt{a^2-c^2}[/tex]
In this case, you can identify in the figure that:
[tex]a=AC=65\ m\\\\b=BC=x\\\\c=AB=63\ m[/tex]
Finally, you must substitute these known values into the equation [tex]b=\sqrt{a^2-c^2}[/tex] and then evaluate in order to find the value of "x". You get that this is:
[tex]x=\sqrt{(65\ m)^2-(63\ m)^2}\\\\x=16\ m[/tex]
