Respuesta :
Rate refers to the speed at which something is done, so your answer is D.
Answer;
how fast or slow something is done.
Explanation;
The term rate refers to how fast or slow something is done. For example; a higher rate shows how fast something is being done or is taking lace, lower rate shows how slow something is being done.
In other words it is a quantity measured with respect to another measured quantity; for instance; a rate of speed of 60 miles per hour.