4 Global spending on the health sector, by both the private and public sectors, is the highest compared with all other sectors including education and defence. Investment in education and the health sector has resulted in new life-saving technology being introduced. However, demand for certain vaccinations has decreased over the years, shifting the demand curve of vaccinations to the left. (a) Define investment. [2] (b) Explain two causes of a shift of a product's demand curve to the left. [4] (c) Analyse, using a production possibility curve diagram (PPC), the effect of increased investment in both education and the health sector. [6] (d) Discuss whether consumers would benefit more from healthcare being provided by the private sector or the public sector. [8]