The process of growing or shrinking a circle from one to the other while maintaining the same shape is called "dilation". Dilation is a transformation that changes the size of a figure but does not alter the shape. It enlarges or reduces a figure by a scale factor, which is the ratio of any side of the image to the corresponding side of the pre-image. Since circles are similar by definition (all circles are similar to each other as they have the same shape and only differ in size), when one circle is transformed into another circle through enlargement or reduction, it is due to the process of dilation.
So, the correct answer is dilation.
