The correct answer is A. Change in income.
A change in income can cause a change in demand, but it is not a cause of a shift in demand. A shift in demand occurs when there is a change in the quantity demanded of a good or service at any given price. A change in income can cause a change in demand, but it does not cause a shift in demand.
A change in price can cause a change in demand. If the price of a good or service decreases, the quantity demanded of that good or service will increase. This is because consumers will be able to afford more of the good or service at a lower price. Conversely, if the price of a good or service increases, the quantity demanded of that good or service will decrease. This is because consumers will be able to afford less of the good or service at a higher price.
A change in fashion can also cause a change in demand. If a particular style of clothing becomes popular, the demand for that style of clothing will increase. Conversely, if a particular style of clothing becomes unpopular, the demand for that style of clothing will decrease.
A change in the prices of substitutes can also cause a change in demand. If the price of a substitute good decreases, the demand for the original good will decrease. This is because consumers will be able to afford more of the substitute good at a lower price, and they will therefore be less likely to purchase the original good. Conversely, if the price of a substitute good increases, the demand for the original good will increase. This is because consumers will be less able to afford the substitute good at a higher price, and they will therefore be more likely to purchase the original good.