A Researcher Studies 45 Volunteer Citizens from a Small Community

A researcher studies 45 volunteer citizens from a small community and asks them about the amount of caffeine (in milligrams) they ingest before and after lunch each day.The null hypothesis for this paired-samples study could be:

A) more caffeine is ingested before lunch.
B) more caffeine is ingested after lunch.
C) there is a difference between the amount of caffeine ingested before and after lunch.
D) there is no difference between the amount of caffeine ingested before and after lunch.