Answer: Quadrant 2
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Explanation:
Check out the diagram below. An example point in the third quadrant is (-2,-5). This quadrant is the southwest quadrant. Reflect the example point over the x axis (aka the line y = 0) and we get (-2,5). This is shown when we go from point A to point B in the diagram.
The reflection rule is [tex](x,y) \to (x,-y)[/tex] showing that only the y coordinate changes from y to -y. If y is negative, then flip to positive, or vice versa. The x coordinate stays the same.
The point started in quadrant 3 and it moves to quadrant 2 after the reflection over the line y = 0.
Side note: all points on the line y = 0 have a y coordinate of 0