Question

Which graph shows a triangle and its reflection image over the x-axis?
A. first picture
B. 2nd picture
C. picture 3
D. picture 4

A. is wrong

Answer 1

Assuming the choices are A,B,C,D in that order from left to right (according to your attachments), then it would be the fourth one. 

To make sure we're on the same page, I'm attaching your fourth drawing below. It's the result of taking a triangle and reflecting it over the horizontal x axis. Think of it like mirroring an image.

Answer 2

Answer-

In picture 4, the triangle is reflected over x axis.

Solution-

While reflecting a point over x axis, (x, y) → (x, -y) rule is followed.

Only the sign of y-coordinate is changed, keeping x-coordinate intact.

In the first picture, though the image is reflected, but it is reflected over y axis.

In the second picture, the image is first reflected over y axis, then it is translated 1 unit down.

We rotating a point 90° clockwise, (x, y) → (y. -x) rule is followed.

In the third picture, the triangle is rotated 90° clockwise and then translated 1 unit to right.

But, in case of the fourth picture, the figure is reflected over x axis. Only the y coordinates sign are changed, all the x coordinates are same as before.