An exceptional demand curve can result from

1. Analyze the question The question asks what can cause an "exceptional demand curve." This is a demand curve that does not follow the normal law of demand. Normally, when price rises, quantity demanded falls, so the curve slopes downward. An exceptional demand curve slopes upward, or behaves unusually, so that a higher price leads to more demand.

2. Explain the concept Exceptional demand curves usually arise from:

• Giffen goods: inferior goods that take up a big part of a poor household's budget.
• Veblen (prestige) goods: luxury goods that people buy because they are expensive.
• Expectation of future price increase: if consumers expect prices to rise further, they buy more now even though the current price has gone up. Speculative buying works the same way.
• Ignorance or a belief that high price means high quality.

3. Go through the options

• A. Increase in price of raw materials: this affects supply and shifts the supply curve to the left. It does not make the demand curve exceptional.
• B. Change in taste of consumer: this is a determinant of demand that shifts the normal demand curve. It does not change its shape or direction.
• C. Increase in the size of the population: this also shifts the demand curve to the right, but the curve stays normal.
• D. Expectation of future price increase: this makes consumers buy more as the price rises, which gives an upward-sloping (exceptional) demand curve. ✔️

4. Answer The correct option is D.

5. Tip Remember the phrase "Giffen, Veblen, Expectation" for exceptional demand. Options that only shift the curve (taste, population, income) are not exceptional demand. Exceptional demand changes the slope of the curve.