Answer
A
Work Step by Step
$x=5\tan 38^{\circ}\implies \tan 38^{\circ}=\frac{x}{5}$
But $\tan\theta=\frac{\text{opposite side}}{\text{adjacent side}}$
This implies that $x$ is the length of the opposite side to the $38^{\circ}$ angle and the length of the side adjacent to it is 5. This is the case in triangle A.
