Concept:A rightward shift in the demand curve is caused by a change in a non-price determinant of demand, such as income, taste, or population.
Explanation:A change in the price of Bournvita only causes a movement along the same demand curve, not a shift.
So a rise or fall in the price of Bournvita will not shift the demand curve.
A tax on cocoa producers affects the cost of production, so it shifts the supply curve, not the demand curve.
An increase in consumer income raises the purchasing power of consumers.
For a normal good like Bournvita, higher income leads to higher demand at every price.
Therefore, the demand curve for Bournvita shifts to the right.
Answer:B. an increase in income