From the given image:

The graph shows that the line $XY$ is the axis of symmetry for the quadrilateral $PQRS$. Based on symmetry:

1. Point $S$ is the reflection of point $Q$ across the line $XY$.
2. To find the coordinates of $S$, observe that $Q$ is at $(3, 7)$.
3. $XY$ is a horizontal line at $y = 5$. The vertical distance of $Q$ above $XY$ is: $7 - 5 = 2$
4. To reflect $Q$, $S$ must be at the same vertical distance below $y = 5$, so: $y = 5 - 2 = 3$
5. The $x$-coordinate of $S$ remains the same as $Q$, since the reflection is vertical.

Thus, the coordinates of $S$ are $(3, 3)$.

Final Answer:

B. (3, 3)

Do you want further clarification or have any questions? Here are some related questions to expand your understanding:

1. How do you determine the coordinates of a reflected point across a line of symmetry?
2. What is the equation of a line of symmetry for a geometric figure?
3. How can symmetry help solve problems in coordinate geometry?
4. What are the properties of reflection across horizontal and vertical lines?
5. Can the coordinates of $P$ and $R$ also be verified using the symmetry line?

Tip: Always check the line of symmetry's equation to ensure accurate reflection calculations.