Final answer:
A beneficiary designation by class, such as 'Children of the insured', refers to naming a group as beneficiaries rather than individuals by their specific names. Option A is the correct answer as it represents a class designation.
Step-by-step explanation:
The question asks which option would be described as a beneficiary designation by class. This refers to a method of designating beneficiaries for an insurance policy or retirement account by a particular category, rather than by individual names. The correct answer is A. Children of the insured. This is a class designation because it refers to a group (or class) of individuals, i.e., the insured's children, without specifying their exact names. On the other hand, a specific named beneficiary would be an individual who is specifically named, such as 'John Doe'. The option 'Estate of the insured' refers to the insured's legal estate, and 'Tertiary beneficiary' is a third-in-line individual or entity designated to receive benefits only if both the primary and secondary beneficiaries are unable to do so.