a) France does just that.

Since 1988.

It was called for years RMI for "Revenu Minimum d'Insertion" which translates to something like minimum revenue for social integration.

Our previous government changed the name to RSA or "Revenu de Solidarité Active", which translates to revenue of active solidarity. They reduced the revenue by a few percent at that occasion.

The RSA provides now enough to live (about 500€ for a single person per month) if not in a major city center. It becomes about 1200€ month for a family with two children. Again, just the minimum to live.

Also take in account that education and health are free* in France.

(*) YMMV, not all MDs, but most schools, etc.