Option 1 -> Incorrect sequence; price rise cannot occur before demand increases.
Option 2 -> Correct sequence following economic causation: demand increases due to heatwave, supply stays constant in short run, buyers compete for limited supply, leading to price rise.
Option 3 -> Incorrect; supply remaining same cannot be the first event triggered by heatwave.
Option 4 -> Incorrect; competition cannot occur before demand increases.
Hence, Option 2: (D), (B), (C), (A) -> During a heatwave, the demand for ice cream increases first (D). In the short run, producers cannot immediately increase supply, so supply remains constant (B). With higher demand and limited supply, competition among buyers intensifies (C). This increased competition and demand-supply gap ultimately causes the price of ice cream to rise (A). This follows the basic economic principle of demand-supply dynamics. -> correct