When reflecting an object over the y-axis, what change occurs to its x-value?

When reflecting an object over the y-axis, the x-coordinate of every point on that object undergoes a specific transformation: it changes its sign. This means that if an object originally has a point with a positive x-value, upon reflection over the y-axis, that x-value will become negative. Conversely, an x-value that is negative will become positive.

For instance, if you have a point at (3, 2), upon reflection over the y-axis, it would move to (-3, 2). Similarly, a point at (-4, 5) would move to (4, 5) when reflected. Hence, the correct choice involves recognizing that the transformation switches the sign of the x-coordinate, effectively moving it from positive to negative or from negative to positive. This consistent property of reflection across the y-axis clearly underlines why the answer is correct.