9708/11 Economics Oct Nov 2013 Online Test | Cambridge AS and A Level MCQ

The diagram shows three production possibility curves (PPC) for a country, labelled 3, 2 and 1. The original PPC for the country is 2.
This country experiences a fall in its working population and then this is followed by a long period of recession.
If an increase in GDP then takes place, what is the increase in production?