Final answer:
The slope of Nylah's writing progress is 10 pages every 3 days. Hence, D) is correct.
Step-by-step explanation:
The slope of a line can be determined by finding the change in the vertical axis (y) divided by the change in the horizontal axis (x). In this case, Nylah plans to write 10 new pages every 3 days. So, the change in pages is 10 and the change in days is 3.
The slope is calculated as 10/3, which simplifies to 3.33. However, since slope represents the rate of change, it is common to round it to the nearest whole number. Therefore, the slope is 3.
Therefore, the correct answer is D) 10.