Some advice on answering these questions

(i) There is one mark for selecting the correct option
(ii) There are three marks for explanation
(iii) It is possible to achieve 3 explanation marks even if the incorrect option has been selected

General advice on good ways to get the three extra marks

1/ Define key terms throughout
2/ Consider the key concept or model that lies behind the question
3/ Apply the information provided e.g. the effects of a tax or a subsidy on a market
4/ Annotate the diagrams provided in the question paper e.g. shading in or labelling areas of consumer & producer surplus, spending on a subsidy or agency spending on a buffer stock
5/ Be prepared to calculate percentages and show your workings, including a relevant formula
6/ Reject one or more of the options – remember to explain why you have rejected them