Which of the following will have positive signs and which will have negative ones:
(a) Price elasticity of demand;
(b) Income elasticity of demand (normal good);
(c) Income elasticity of demand (inferior good);
(d) Cross elasticity of demand (with respect to changes in price of a substitute good);
(e) Cross elasticity of demand (with respect to changes in price of a complementary good);
(f) Price elasticity of supply?