Are the two insurances and three insurances of social security randomly selected from the five insurances? Is there a rule that you must choose something?

If an individual is insured, he can only be insured for old-age care and medical care.

The rest of the maternity, work injury and unemployment must be handled by the unit.

According to the regulations, all five insurance companies should handle it for employees. If you must say two or three insurances, it definitely includes old-age care, generally including medical care. The remaining one may be a work-related injury, which may be childbirth.