Unit 1: Russian drinkers and price elasticity of demand

....appear to be drinking more beer and less vodka, depite tax increases according to the BBC

http://www.bbc.co.uk/news/13576896

a) In economic terms, what are beer and vodka?
b)Given the increase in price and fall in sales mentioned, do you believe the PED for beer to be elastic or inelastic?
c) Explain why this is the case using economic theory