What does a line of symmetry do to a figure?

A line of symmetry is a line that divides a figure into two mirror-image halves. When a figure is folded along this line, the two resulting parts match perfectly, indicating that they are congruent. This means that each part has the same shape and size, ensuring that the figure is symmetric about the line. Understanding this concept is essential in geometry, as symmetry is a foundational principle used in various mathematical contexts.

The other choices do not align with the definition of a line of symmetry. For example, creating a larger figure or changing the size are actions that would alter the dimensions of the original shape, which is not the function of a line of symmetry. Similarly, eliminating parts of the figure suggests a loss of material rather than a division into equal sections. Therefore, the correct choice highlights the key characteristic of symmetry, which is the creation of two congruent parts.