C can make up for a lot depending on your network and skills. I'm not particularly well-embedded in my local community and if necessary I could get at least the following things free:
* Car repair work
* Basic healthcare (luckily I have state insurance so I don't need it, but if I did it's possible)
* Home/apartment/other home repair or improvement
* Tailoring/alterations/well-fitting clothing (including free clothes if I ask - even if I don't, I get given clothing on a semi-regular basis)
* Cooking equipment
Now, in return I need to offer some skills (mostly technical, academic, or navigating bureaucracies - skills that are in fairly short supply on the lowest part of socioeconomic ladder), but like I said, I'm not particularly involved so people with more history and social credit can get more stuff taken care of.
I also at one point paid like...50% of market rate for rent because I was willing to be free, on-call childcare for 3 children under the age of 7.
A) Their partner or family works
B) Welfare
C) Informal economy
There's also the 4th but unlikely in this case
D) Investments