To solve this problem, we need to identify the line of reflection that maps rhombus PQRS onto rhombus JKLM.

Let's analyze the options given:

1. y = 1: This is a horizontal line at $y = 1$.
2. x = 1: This is a vertical line at $x = 1$.
3. y = x: This is a diagonal line passing through points where $y = x$.
4. y-axis: This is the vertical line $x = 0$.

Observing the rhombi:

• Rhombus PQRS and rhombus JKLM appear to be symmetric across a line.
• Both rhombi seem to be reflected over a diagonal line based on their relative positions.

Verifying the reflection line:

Since both rhombi are mirrored diagonally, the line of reflection is likely to be the line y = x, which reflects points along this diagonal line.

Thus, the correct line of reflection is y = x.

Would you like a more detailed explanation of reflections or transformations?

Here are some follow-up questions to explore this topic further:

1. What properties of a rhombus remain unchanged after a reflection?
2. How do you determine the line of reflection for two given shapes?
3. What is the effect of reflecting a point across the line $y = x$?
4. Can a shape be mapped onto itself through reflection? If yes, under what conditions?
5. How can you identify symmetry in geometric figures using coordinate geometry?

Tip: Reflections over diagonal lines like $y = x$ switch the coordinates of any point, transforming $(x, y)$ into $(y, x)$.