If the graph of an object's position over time is a horizontal line and \( y \) is not equal to 0, this indicates that the object's position is constant over time.
In this case, we can draw the following conclusions:
- The velocity of the object is zero, because it is not changing position.
- The acceleration can be considered constant and is actually zero, since the object is not speeding up or slowing down.
Therefore, the correct response is:
The velocity is zero.