When there is a sudden increase in temperature at a place, the relative humidity typically decreases. This decrease occurs because warmer air has a higher capacity to hold moisture compared to cooler air. As the temperature rises, the air’s ability to retain water vapor increases, causing the relative humidity to drop unless there is a corresponding increase in the absolute humidity (amount of water vapor in the air).

However, if there is no significant change in the moisture content of the air, the relative humidity will decrease due to the relative relationship between the actual water vapor content and the maximum possible water vapor content at the new, higher temperature. Therefore, in most cases, a sudden increase in temperature leads to a decrease in relative humidity, making [B] Decreases the correct answer.