Answer:
c) H0: µ = 7 hours (null hypothesis)
H1: µ < 7 hours (alternative hypothesis and original claim)
Explanation:
The hypothesis test is performed in order to see if a sample outcome gives evidence to reject a null hypothesis and support the researchers claim.
In this case, the claim is that the mean amount of sleep for adults is less than 7 hours.
For this claim, the alternative hypothesis will state the researcher's claim: the mean amount of sleep for adults is significantly less than 7 hours.
The null hypothesis will state the opposite: the mean amount of sleep for adults is not significantly less than 7 hours. In this case, it is the same to claim that the mean amount is 7 hours.
Then, the null and alternative hypothesis are: