Answer :
This would be the null hypothesis.
A decision to reject this hypothesis means that the mean life span is less than 2.8 years. A decision to fail to reject this hypothesis means that the life span is indeed at least 2.8 years.
A decision to reject this hypothesis means that the mean life span is less than 2.8 years. A decision to fail to reject this hypothesis means that the life span is indeed at least 2.8 years.