V. Choose the correct answer A, B, C or D to complete the passage.

People need to breathe. If they don’t breathe, they ___(1)___ die. But how clean is the air people breathe? If they breathe ___(2)___ air, they will have breathing problems. Plants and animals need ___(3)___ air too. A lot of the things in our lives create harmful gases and ___(4)___ the air dirty, like cars, motorbikes, and factories. Dirty air is called polluted air. Air pollution can also make our Earth warmer.