Final answer:
c) Interval measurement. The type of measurement being used to measure "processing speed" by using reaction time is Interval measurement.
Step-by-step explanation:
The type of measurement being used to measure "processing speed" by using reaction time is Interval measurement.
Interval measurement is a level of measurement in which the data has a definite ordering and the differences between the data can be measured. In this case, the reaction time is being used as a measure of processing speed, where shorter reaction times indicate faster processing speed.
For example, if a researcher measures the average reaction time of participants in a task, they can compare the reaction times to determine which individuals have faster processing speed.