Statistics
a study compared paired daytime and nighttime counts of blue catfish, flathead catfish, and channel catfish made by the same divers in five lakes during july 2015. overall, they counted 238 catfish during the day and 417 catfish at night. the researchers speculate that catfish counted at night were present during the day, but were hidden from view. biologists should consider that catfish behavior and susceptibility to being seen might vary a great deal between daytime and nighttime, even during the summer. in some lakes, the majority of catfish may not be seen during the daytime. determine whether the study is an observational study or an experiment. justify your answer with specific references to the information in the study.

a.) observational study, because the divers are not catching catfish for a sample
b.) experimental study, because the divers are catching catfish for a sample
c.) observational study, because the divers are watching the catfish only during the day
d.) experimental study, because the divers are watching the catfish during the day and night
e.) unable to determine whether this is an observational study or experiment