The correct answer is: A. animation-pause-state
The animation-pause-state CSS property defines whether the animation is running or paused. It can be used to pause an animation at any time, and to resume it later. The animation-pause-state property can be used to create a variety of effects, such as making an element appear to disappear and reappear, or making it move in a jerky or stuttering motion.
The animation-state CSS property is a shorthand property for the animation-play-state and animation-pause-state properties. It can be used to set both the animation-play-state and animation-pause-state properties at the same time.
The animation-play-state CSS property defines whether the animation is playing or paused. It can be used to start or stop an animation. The animation-play-state property can be used to create a variety of effects, such as making an element appear to move in a continuous motion, or making it appear to jump from one position to another.
Therefore, the animation-pause-state property is the only property that defines whether the animation is running or paused.