A rectangle is dilated by a scale factor of [tex]$n=1$[/tex]. Which statement is true regarding the image of the dilation?

A. The image will be smaller than the pre-image because [tex]$n=1$[/tex].
B. The image will be congruent to the pre-image because [tex]$n=1$[/tex].
C. The image will be larger than the pre-image because [tex]$n=1$[/tex].
D. The image will be a triangle because [tex]$n=1$[/tex].

When we dilate a geometric figure, each point on the figure is moved away from or towards a fixed point (the center of dilation) by a certain multiplier known as the scale factor. The effect of this dilation on the figure's dimensions is dictated by the value of the scale factor $ n $.

In this scenario, the scale factor $ n $ is given to be 1. Here’s a detailed explanation regarding the implications of a scale factor of 1:

1. Understanding Dilation with Scale Factor 1:
- Dilation involves resizing the figure but retaining its shape.
- If the scale factor $ n = 1 $, every point on the figure remains the same distance from the center of dilation.
- Therefore, each dimension (length and width) of the rectangle remains unchanged after dilation.

2. Effect on the Geometry of the Figure:
- Since the dimensions remain unchanged, the new image produced will be identical in size and shape to the original pre-image.
- This means the image resulting from the dilation will be congruent to the pre-image. Congruency indicates that the figures have the same size and shape.

3. Analyzing the Given Statements:
- "The image will be smaller than the pre-image because $ n = 1 $."
This statement is false because the image size does not change; it stays the same.

- "The image will be congruent to the pre-image because $ n = 1 $."
This statement is true. Since dilation with $ n = 1 $ does not alter the size of the figure, the image remains congruent to the pre-image.

- "The image will be larger than the pre-image because $ n = 1 $."
This statement is false because there is no increase in size when $ n = 1 $.

- "The image will be a triangle because $ n = 1 $."
This statement is false as dilation affects the size and position of the figure but retains its shape. A rectangle remains a rectangle after dilation with any scale factor, including 1.

Given the analysis, the correct statement regarding the image of the dilation is:

"The image will be congruent to the pre-image because $ n = 1 $."

Thus, the index of the true statement is 2.