During a thunderstorm, the thunder in the skies is produced by the 1. meeting of cumulonimbus clouds in the sky 2. lightning that separates the nimbus clouds 3. violent upward movement of air and water particles Select the correct answer using the codes given below.

1. Thunder is the sound produced by the rapid heating and expansion of the air surrounding a lightning discharge during a thunderstorm. 2. Lightning heats the channel of air through which it passes to extremely high temperatures (up to 30,000 °C) almost instantaneously. 3. This intense heating causes the air to expand explosively, creating a shock wave that propagates through the atmosphere. This shock wave is heard as thunder. 4. Statement 1 is incorrect. The mere meeting of cumulonimbus clouds does not produce thunder; lightning is required. 5. Statement 2 incorrectly describes the mechanism. Lightning causes the thunder, but it doesn't do so by separating clouds; it does so by rapidly heating the air. 6. Statement 3 describes updrafts within a thunderstorm cloud (cumulonimbus). These violent upward movements contribute to charge separation, which leads to lightning, but the air/water movement itself is not the direct cause of the sound of thunder. 7. Since none of the options accurately describe the direct physical process that produces thunder (rapid expansion of air due to heating by lightning), option (D) is the most appropriate answer.