When does inflation occur?

when demand for a high-priced good is reduced, resulting in unemployment
when supply of a good exceeds demand for that good, and the price must be reduced
when demand for a product goes up, and the product becomes more expensive
when the price of a good or service increases, but the value of a dollar remains the same

answer: d. when the price of a good or service increases, but the value of a dollar remains the same.