If we want to investigate the effectiveness of taking vitamins in preventing cancer, we recruit a group of subjects and ask them if they regularly take vitamins. The subjects who regularly take vitamins exhibit better health on average than those who do not. Does this prove that regularly take vitamins is effective in cancer prevention?
A There is not enough Information
B It does not
C It does
D It depends
reason is is that in the text it only says that they are healthy it does not say anything about the subjects having cancer and you know what the answer is actually c
