D) decreases, inverse
Explanation:
The average speed of each lap decreases. This is an example of an inverse relationship.
Speed is the rate of change of distance with time. In calculating the average speed, we should understand that the total length of path is taken into consideration and so is the total time taken.
Average speed = 
It was explained that after every 5 seconds the speed of the runner becomes slower.
There is definitely an inverse relationship between average speed and the total time taken.
An inverse relationship is such that as one variable increases, the other diminishes.
As average speed reduces the time taken increases.
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Speed brainly.com/question/1386181
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