23) D

Let us find the GPE when the cyclist is 100m in vertical height. Also, this is the amount of GPE that will be lost when the cyclist descends 100m.GPE = mgh = 100 x 10 x 100 = 100,000 J

To find the resistive force, we need to use the formula : Work done = Force x Distance
Rearranging to get Force, we get Force = Work done/Distance

In order to find the distance, we need to use the 1 in 10 information that is given to us.
We know that the cyclist descends 100m in vertical height.
Using the ratio of 1 : 10, we get 100 : 1000
So the distance travelled by the cyclist = 1000m

Work done is equal to the GPE lost by the cyclist.

Force = 100,000 ÷ 1000 = 100N