1. **Problem Statement:** We are given two triangles, \(\triangle ABC\) and \(\triangle A'B'C'\), where \(\triangle A'B'C' \cong \triangle ABC\). We need to describe the transformation from \(\triangle ABC\) to \(\triangle A'B'C'\) and confirm if they are congruent. 2. **Understanding Transformations:** The problem states that \(\triangle A'B'C'\) is a reflection of \(\triangle ABC\) across the y-axis followed by a translation left. Reflections and translations are examples of rigid transformations. 3. **Rigid Transformations:** Rigid transformations preserve the size and shape of figures, meaning side lengths and angles remain unchanged. Therefore, the original figure and its image are congruent. 4. **Analyzing the Options:** - Option A mentions reflection across the y-axis and translation left 7, but incorrectly states rigid transformations dilate the figure (which is false). - Option B mentions reflection across the x-axis and translation left 5, which does not match the problem description. - Option C mentions reflection across the y-axis and translation left 5, correctly stating rigid transformations have no effect on side lengths. - Option D mentions reflection across line p and translation left 7, which is not specified. 5. **Conclusion:** The correct description is Option C: \(\triangle ABC\) is reflected across the y-axis and translated left 5 units. Since reflection and translation are rigid transformations, \(\triangle A'B'C' \cong \triangle ABC\). **Final answer:** Option C is correct.