Option 4: (A) - (IV), (B) - (I), (C) - (II), (D) - (III) -> Let's match each correctly:
(A) Increase in price of goods X → (IV) Contraction in demand for good X: When price increases, quantity demanded decreases along the same demand curve, known as contraction in demand.
(B) Increase in income of consumers → (I) Increase in demand for normal goods: Normal goods see higher demand when consumer income rises, as people can afford more.
(C) Good X is a necessary good → (II) Demand is price inelastic: Necessary goods (like food, medicines) have inelastic demand because consumers buy them regardless of price changes.
(D) Demand curve of Good X is a rectangular hyperbola → (III) Unit elasticity of demand: A rectangular hyperbola represents the equation P × Q = constant, which mathematically represents unit elastic demand (elasticity = 1). -> correct