Which of the following hypotheses can be tested with experiments? select all that apply 1.) a diet low in sugar reduces the risk for heart disease
2.) coffee increases subject performance on intelligence tests
3.) people that brush their teeth live longer than those who don't brush their teeth
4.) scientists will find a cure for cancer before the year 2020

I know that 4 isn't the answer so I selected the other three and it said I was wrong. isn't a hypotheses something that can be experimented on so can't all of the three have experiments If I'm making sense ​