Answer:
change in demand; shift of the demand curve.
Step-by-step explanation:
We know that income elasticity of demand derives by considering the percentage change in quantity demanded and percentage change in income
In mathematically,
Income elasticity of demand = (percentage change in quantity demanded) ÷ (percentage change in income)
By considering the above information, the change in income preferences is due to change in demand plus it also shift of the demand curve