ANSWER
A. The object has a negative velocity
Step-by-step explanation
We want to describe the slope of a position-time graph that is negative.
If the slope of a position-time graph is negative, it implies that the velocity is also negative. In other words, as time increases, the velocity also decreases.
As velocity decreases, it implies that the acceleration also decreases.
Therefore, we have that the acceleration of the object is negative.
The answer is option A.