Answer:
A system of basic services for citizens at every stage of life is a cradle-to-grave system.
Explanation:
1 is not correct because it represents the production in an economy in a particular time frame (usually a year).
2 is not correct because it doesn't provide service to all of the age groups.
3 is not correct because it is not meant to provide services to all age groups.
4 is correct because it is a system that provides services to all citizens, from all age groups, or rather from their birth to their death, thus throughout all of their life stages.
