Triangle A B C lies in the first quadrant. Points A, B, and C are reflected across the line y=x to points A^{\prime}, B^{\prime}, and C^{\prime}, respectively. Assume that none of the vertices of the triangle lie on the line y=x. Which of the following statements is not always true?
Answer Choices
A. Triangle A^{\prime} B^{\prime} C^{\prime} lies in the first quadrant.
B. Triangles A B C and A^{\prime} B^{\prime} C^{\prime} have the same area.
C. The slope of line A A^{\prime} is -1 .
D. The slopes of lines A A^{\prime} and C C^{\prime} are the same.
E. Lines A B and A^{\prime} B^{\prime} are perpendicular to each other.