Answer:
D. 8
Explanation:
If we divide the number of riders of a day by the number of riders of the day before, we get:
[tex]\begin{gathered} \frac{56}{7}=8 \\ \frac{448}{56}=8 \\ \frac{3,584}{446}=8 \\ \frac{26,672}{3,584}=8 \end{gathered}[/tex]Therefore, the number of riders changes each day by a factor of 8 because each day the number of riders is 8 times the number of riders of the day before.