Low air pressure usually means bad weather. this is because
warm air rises and condenses, usually forming clouds and precipitation
cold air rises, forming clouds and precipitation
high pressure brings in cold air to the low pressure area
cool air is usually full of moisture, which makes it humid and rainy

The answer is:

warm air rises and condenses, usually forming clouds and precipitation

In order to understand this you have to think that as hot air containing water vapor and other gases rises it cools down, and creates clouds that will continue to rise and cool down even more, this will eventually create precipitation.

"choosing is refusing" means individuals face an opportunity cost with each decision they make. economists state that every decision involves trade-offs. opportunity cost is the least desirable alternative given up as a result of a decision.

answer; they burn down the bushes and trees;