Based on the options provided for the purposes served by Paragraph 8, the following selections can be made:
- to illustrate that some animal cycles are related to light
- to show that animals can consciously reset their internal clocks
- to give an example of how an animal’s internal clock reacts to light
The other options do not seem to align with the purposes mentioned in Paragraph 8. If you have the text of Paragraph 8 or more context, please share it for a more thorough analysis.