Answer:
The height is remaining constant over time.
If x was y and y was x then; when something on x stays the same the height would change too and stay constant.
But as we speak of height staying constant and time progressing time becomes constant for that reference but it is stated over time.
Step-by-step explanation:
In physics and chemistry, the law of conservation of energy states that the total energy of an isolated system remains constant; it is said to be conserved over time. ... For instance, chemical energy is converted to kinetic energy when a stick of dynamite explodes.
So for graphs any activity that does not move in increase or decrease it stays constant / added it stays constant over time.
