Answer:
triangle E
Explanation:
imagine the X-axis as a mirror, the mirror reflects the shape or the body, and you'll see that the same distance you're away from the mirror as your reflection distance
if you want to prove that the triangle E is the reflection of the triangle A, count from the nearest point from the X-axis, you'll count 3 to reach the X-axis ,and the difference will be also 3 from the X-axis to the nearest point to the triangle E