The correct answer is B. ozone depletion.
Ozone depletion is the thinning of Earth’s ozone layer in the stratosphere, resulting from human-made chemicals that release chlorine and bromine when they interact with sunlight. Ozone depletion is a serious environmental problem because it increases the amount of ultraviolet radiation that reaches Earth’s surface. Ultraviolet radiation can cause skin cancer, cataracts, and other health problems.
A. Ozone accumulation is not a problem. Ozone is a gas that is found in Earth’s atmosphere. It is important because it protects life on Earth from harmful ultraviolet radiation from the sun.
C. Acid rain is a form of precipitation that is caused by air pollution. Acid rain can damage forests, lakes, and other ecosystems. It can also cause health problems in humans and animals.
D. Allergens are substances that can cause an allergic reaction in some people. Allergic reactions can range from mild to severe.