you need to understand what is transfer of payments? if you understand it . .then whether the examiner asks it in social mobility or poverty ...there should be no problem ...
in fact it is related to both of the issues...
people are poor so they need transfer of payments...but when they get transfer payments do they get rich ? or do they get used to it ? they get lethargic and do not work hard?
or transfer payments are completely useless ? since it only adds burden to the economy ?
these are the questions that you need to clear in your mind. once you understand it ..then you can write it in poverty or social mobility or anywhere else