The answer is: A. Standard lives
Standard lives are those whose anticipated mortality corresponds to the standard lives represented by the mortality table. They are considered to be the lowest risk group and are charged the lowest premiums.
Preferred risks are those who are considered to be at a lower risk of death than standard lives. They are charged lower premiums than standard lives, but higher premiums than declined lives.
Sub-standard lives are those who are considered to be at a higher risk of death than standard lives. They are charged higher premiums than standard lives and preferred risks.
Declined lives are those who are considered to be at too high a risk of death to be insured by most insurers. They are not offered insurance by most insurers, or are offered insurance at very high premiums.