Answer:
Triangle DEF
Explanation:
Hi there!
A translation of a shape occurs when all the coordinates of the original image is shifted up, down, left or right by an equal value.
Triangle ABC is a reflection of the grey triangle across the y-axis. We know this because the y-axis acts like a line of symmetry between the two shapes.
Triangle DEF appears as if it's been shifted. Therefore, triangle DEF is a translation of the grey triangle.
I hope this helps!