biology mitosis aqa alevel question

Use the curve for the concentration of DNA to find the length of a cell cycle in these yeast cells. Explain how you arrived at your answer.
answer:
1. 3 hours;
2. Time between beginnings / endings DNA replication / Increases / levelling outs
of DNA concentration / for shape (of curve for replication) to be repeated;
3. (DNA) replication takes place once per cell cycle

how do u get this (graph link page 6)
https://pmt.physicsandmathstutor.com/download/Biology/A-level/Topic-Qs/AQA-Old/Unit-2/Set-2/The%20Cell%20Cycle.pdf

From the graph you can see that the cycle repeats every 3 hours because the same shape is repeated every 3 hours. You then describe the shape that is repeated for the second mark. Then for the third mark you use the other line on the graph which represents the numebr of yeast cells

ok but what does the 2nd point even mean? they just wrote a bunch of words it doesn't make sense to me and for the 3rd point i get it, but why do u need to mention it i wouldn't have thought about it