Final answer:
The change in any factor other than price, such as income, consumer preferences, population characteristics, and the prices of related goods, will shift the demand curve. Changes in the interest rate represent a price change and only cause movement along the demand curve.
Step-by-step explanation:
The main answer to the question about what factor other than price would shift the demand curve is c. Price. Changes in the price level of a good or service will typically result in a movement along the demand curve, rather than shifting the curve entirely. However, a change in other factors, such as income, tastes and preferences, the composition or size of the population, and the prices of related goods, can shift the demand curve either to the right (indicating an increase in demand) or to the left (indicating a decrease in demand).An explanation of why changes in the interest rate cause a movement along the demand curve is because the interest rate is considered the price of financial capital. Hence, when the interest rate changes, it affects the cost of borrowing, which in turn influences the quantity demanded without altering consumers' underlying preferences or desires for goods and services. In contrast, non-price variables such as consumer confidence, expectations, and demographic shifts alter consumers' demand for goods and services independently of price changes, causing the entire demand curve to shift.In conclusion, while price changes result in movements along the demand curve, it is the changes in other factors that cause the entire demand curve to shift. The options a. Weather and b. interest rate are incorrect as they are not the types of changes that would shift the demand curve.