Within a PPF framework, explain each of the following: (a) a disagreement between a person who favors more domes-tic welfare spending and one who favors more national defense spending, (b) an increase in the population, and (c) a technological change that makes resources less specialized.

It is a downward sloping curve as more of one good can be produced by sacrifising other good, same resources & technology.
It is concave curve because of increasing marginal opportunity cost, i.e increasing amounts of a good to be sacrifised to gain additional amount of other good, as resources are not equally efficient in production of both goods.
Points on PPC reflect full utilisation, points under PPC reflect under utilisation, points above PPC are unattainable.

a) A disagreement between persons favouring more domestic welfare spending or national welfare spending : Is just an issue of reallocation of same resources, technology. So, PPC doesn't change & there can only be movement on the PPC (more of one good, less of other good)

b) An increase in population : leads to increase in human resource & hence the PPC shifts outwards / rightwards as the production potential of economy rise with more human resource.

c) Technological change that make resources less specialised : would reduce resources' efficiency gap in production of two goods. So, Marginal Opportunity cost reduces & hence the PPC becomes less concave.