Which law states that the time taken to move to a target is a function of the target size and the distance to the target?

Fitts' Law is the correct choice because it specifically addresses the relationship between the distance to a target and the size of the target when it comes to human motor movement, particularly in the context of pointing or clicking in user interfaces. It posits that the time required to reach a target is determined by both the distance to the target and its size. In practical terms, larger targets that are closer to the user can be selected more quickly than smaller, more distant targets. This principle is critical in user experience design as it guides designers to create interfaces that enhance usability by considering target sizes and their spatial distribution.

The other laws mentioned have different focuses. Hick's Law deals with decision-making and the time it takes to make a choice based on the number of options available, while Gestalt Law pertains to perceptual grouping, explaining how we naturally organize visual elements. Miller's Law is centered on the capacity of short-term memory, often summarized as the idea that people can hold about seven pieces of information at once. Each of these laws contributes to our understanding of user behavior and interaction, but Fitts' Law directly relates to movement and targeting in UX design.