The correct answer is option-1: Hot, dry and windy condition. Transpiration is the process of water loss from plants through small openings called stomata on their leaves. During hot, dry and windy conditions, the temperature increases, causing the water in the plant to evaporate more rapidly. The dryness of the air also creates a higher concentration gradient, which facilitates the movement of water molecules from the plant to the surrounding environment. Additionally, the wind promotes movement of water vapor away from the leaf surface, further increasing the rate of transpiration. Therefore, all these factors combined result in an increase in transpiration in hot, dry and windy conditions. The other options (2, 3, and 4) involve conditions that either have higher moisture content, cooler temperatures, or still air, which would decrease transpiration.