For alarm clock supply, price rises from $10 to $11 and quantity supplied rises from 80 to 88 units. Using the midpoint method, what is the price elasticity of supply over this interval?

1. Percentage change in quantity: (88 minus 80) divided by the average of 88 and 80, which is 84, times 100, is about 9.52 percent. 2. Percentage change in price: (11 minus 10) divided by the average of 11 and 10, which is 10.5, times 100, is about 9.52 percent. 3. Price elasticity of supply equals 9.52 divided by 9.52, which is exactly 1.00. 4. An elasticity of exactly one is unit elastic, not elastic or inelastic. 5. Option A's 2.83 belongs to the lower-price alarm clock interval, where the percentage quantity change was much larger than the percentage price change. 6. Option B comes from a different point along this same supply table, and option D comes from an unrelated demand elasticity calculation. _Source: OpenStax Principles of Microeconomics for AP Courses (CC BY 4.0), Ch 5 "Elasticity", section 5.1 | Price Elasticity of Demand and Price Elasticity of Supply_