Geometry

Question Analysis：
This question examines whether the translation direction is parallel or perpendicular to the mirror line.
The main focus is identifying if the transformation meets the directional condition for a glide reflection.

Key Concept Explanation：
Glide reflection = reflection + translation parallel to the reflection line
y = -1 is a horizontal line
A translation downward = vertical → perpendicular to horizontal

Step-by-Step Solution：
Reflection over horizontal line y = -1
Translation is downward → vertical direction
Horizontal vs. vertical = perpendicular, so not a glide reflection

Option Analysis：
A – Incorrect: violates the "parallel" requirement
B – Incorrect: no rotation involved
C – ...