Question

Which two triangles are reflections of each other across the x-axis?

Answer 1

Answer: Triangle A and Triangle C

The x axis is the horizontal flat axis (think of it as the ground). Reflect triangle A over this horizontal line and you end up with triangle C. The same can be said in reverse from C to A.

Answer 2

Triangle A&C because it’s just taking the triangle and flipping it upside down

Also
For number 5 the answer is C&D