Weber's law states that are a function of the initial stimulus intensity. absolute thresholds signal detection just noticeable differences false alarms sensorimotor thresholds

The answer is, "Just noticeable differences."

Weber's law was named after Ernst Weber, a German psychologist. The law postulates that the strength and intensity needed to identify changes in a stimulant correlates to the magnitude of the stimulant. In other words, the more severe a stimulus is, a greater change needs to be made for it to be noticed. 

It’s either d or b ! but it might be b